diff --git a/plugins/samplesource/airspy/airspygui.cpp b/plugins/samplesource/airspy/airspygui.cpp
index 705e67926..81b38db59 100644
--- a/plugins/samplesource/airspy/airspygui.cpp
+++ b/plugins/samplesource/airspy/airspygui.cpp
@@ -52,8 +52,7 @@ AirspyGui::AirspyGui(DeviceSourceAPI *deviceAPI, QWidget* parent) :
 
 	m_rates = ((AirspyInput*) m_sampleSource)->getSampleRates();
 	displaySampleRates();
-	connect(m_sampleSource->getOutputMessageQueueToGUI(), SIGNAL(messageEnqueued()), this, SLOT(handleSourceMessages()));
-    connect(m_deviceAPI->getDeviceEngineOutputMessageQueue(), SIGNAL(messageEnqueued()), this, SLOT(handleDSPMessages()), Qt::QueuedConnection);
+    connect(&m_inputMessageQueue, SIGNAL(messageEnqueued()), this, SLOT(handleInputMessages()), Qt::QueuedConnection);
 }
 
 AirspyGui::~AirspyGui()
@@ -128,42 +127,34 @@ bool AirspyGui::handleMessage(const Message& message __attribute__((unused)))
 //	}
 }
 
-void AirspyGui::handleDSPMessages()
+void AirspyGui::handleInputMessages()
 {
     Message* message;
 
-    while ((message = m_deviceAPI->getDeviceEngineOutputMessageQueue()->pop()) != 0)
+    while ((message = m_inputMessageQueue.pop()) != 0)
     {
-        qDebug("AirspyGui::handleDSPMessages: message: %s", message->getIdentifier());
+        qDebug("AirspyGui::handleInputMessages: message: %s", message->getIdentifier());
 
         if (DSPSignalNotification::match(*message))
         {
             DSPSignalNotification* notif = (DSPSignalNotification*) message;
             m_sampleRate = notif->getSampleRate();
             m_deviceCenterFrequency = notif->getCenterFrequency();
-            qDebug("AirspyGui::handleDSPMessages: SampleRate:%d, CenterFrequency:%llu", notif->getSampleRate(), notif->getCenterFrequency());
+            qDebug("AirspyGui::handleInputMessages: DSPSignalNotification: SampleRate:%d, CenterFrequency:%llu", notif->getSampleRate(), notif->getCenterFrequency());
             updateSampleRateAndFrequency();
 
             delete message;
         }
+        else
+        {
+            if (handleMessage(*message))
+            {
+                delete message;
+            }
+        }
     }
 }
 
-void AirspyGui::handleSourceMessages()
-{
-	Message* message;
-
-	while ((message = m_sampleSource->getOutputMessageQueueToGUI()->pop()) != 0)
-	{
-		qDebug("AirspyGui::HandleSourceMessages: message: %s", message->getIdentifier());
-
-		if (handleMessage(*message))
-		{
-			delete message;
-		}
-	}
-}
-
 void AirspyGui::updateSampleRateAndFrequency()
 {
     m_deviceAPI->getSpectrum()->setSampleRate(m_sampleRate);
diff --git a/plugins/samplesource/airspy/airspygui.h b/plugins/samplesource/airspy/airspygui.h
index 475ea652b..145caca75 100644
--- a/plugins/samplesource/airspy/airspygui.h
+++ b/plugins/samplesource/airspy/airspygui.h
@@ -74,7 +74,6 @@ private:
     void updateSampleRateAndFrequency();
 
 private slots:
-    void handleDSPMessages();
 	void on_centerFrequency_changed(quint64 value);
 	void on_LOppm_valueChanged(int value);
 	void on_dcOffset_toggled(bool checked);
@@ -92,7 +91,7 @@ private slots:
     void on_record_toggled(bool checked);
 	void updateHardware();
     void updateStatus();
-	void handleSourceMessages();
+	void handleInputMessages();
 };
 
 #endif // INCLUDE_AIRSPYGUI_H
diff --git a/plugins/samplesource/bladerfinput/bladerfinputgui.cpp b/plugins/samplesource/bladerfinput/bladerfinputgui.cpp
index b252a20d8..a753326a6 100644
--- a/plugins/samplesource/bladerfinput/bladerfinputgui.cpp
+++ b/plugins/samplesource/bladerfinput/bladerfinputgui.cpp
@@ -59,7 +59,7 @@ BladerfInputGui::BladerfInputGui(DeviceSourceAPI *deviceAPI, QWidget* parent) :
 
 	displaySettings();
 
-    connect(m_deviceAPI->getDeviceEngineOutputMessageQueue(), SIGNAL(messageEnqueued()), this, SLOT(handleDSPMessages()), Qt::QueuedConnection);
+	connect(&m_inputMessageQueue, SIGNAL(messageEnqueued()), this, SLOT(handleInputMessages()), Qt::QueuedConnection);
 }
 
 BladerfInputGui::~BladerfInputGui()
@@ -123,20 +123,20 @@ bool BladerfInputGui::handleMessage(const Message& message __attribute__((unused
     return false;
 }
 
-void BladerfInputGui::handleDSPMessages()
+void BladerfInputGui::handleInputMessages()
 {
     Message* message;
 
-    while ((message = m_deviceAPI->getDeviceEngineOutputMessageQueue()->pop()) != 0)
+    while ((message = m_inputMessageQueue.pop()) != 0)
     {
-        qDebug("BladerfGui::handleDSPMessages: message: %s", message->getIdentifier());
+        qDebug("BladerfGui::handleInputMessages: message: %s", message->getIdentifier());
 
         if (DSPSignalNotification::match(*message))
         {
             DSPSignalNotification* notif = (DSPSignalNotification*) message;
             m_sampleRate = notif->getSampleRate();
             m_deviceCenterFrequency = notif->getCenterFrequency();
-            qDebug("BladerfGui::handleDSPMessages: SampleRate:%d, CenterFrequency:%llu", notif->getSampleRate(), notif->getCenterFrequency());
+            qDebug("BladerfGui::handleInputMessages: DSPSignalNotification: SampleRate:%d, CenterFrequency:%llu", notif->getSampleRate(), notif->getCenterFrequency());
             updateSampleRateAndFrequency();
 
             delete message;
diff --git a/plugins/samplesource/bladerfinput/bladerfinputgui.h b/plugins/samplesource/bladerfinput/bladerfinputgui.h
index 686516bf6..234e29197 100644
--- a/plugins/samplesource/bladerfinput/bladerfinputgui.h
+++ b/plugins/samplesource/bladerfinput/bladerfinputgui.h
@@ -70,7 +70,7 @@ private:
 	void updateSampleRateAndFrequency();
 
 private slots:
-    void handleDSPMessages();
+    void handleInputMessages();
 	void on_centerFrequency_changed(quint64 value);
     void on_sampleRate_changed(quint64 value);
 	void on_dcOffset_toggled(bool checked);
diff --git a/plugins/samplesource/fcdpro/fcdprogui.cpp b/plugins/samplesource/fcdpro/fcdprogui.cpp
index 101857a44..0ffb02b08 100644
--- a/plugins/samplesource/fcdpro/fcdprogui.cpp
+++ b/plugins/samplesource/fcdpro/fcdprogui.cpp
@@ -142,7 +142,7 @@ FCDProGui::FCDProGui(DeviceSourceAPI *deviceAPI, QWidget* parent) :
 
 	displaySettings();
 
-    connect(m_deviceAPI->getDeviceEngineOutputMessageQueue(), SIGNAL(messageEnqueued()), this, SLOT(handleDSPMessages()), Qt::QueuedConnection);
+	connect(&m_inputMessageQueue, SIGNAL(messageEnqueued()), this, SLOT(handleInputMessages()), Qt::QueuedConnection);
 }
 
 FCDProGui::~FCDProGui()
@@ -209,20 +209,20 @@ bool FCDProGui::handleMessage(const Message& message __attribute__((unused)))
 	return false;
 }
 
-void FCDProGui::handleDSPMessages()
+void FCDProGui::handleInputMessages()
 {
     Message* message;
 
-    while ((message = m_deviceAPI->getDeviceEngineOutputMessageQueue()->pop()) != 0)
+    while ((message = m_inputMessageQueue.pop()) != 0)
     {
-        qDebug("FCDProGui::handleDSPMessages: message: %s", message->getIdentifier());
+        qDebug("FCDProGui::handleInputMessages: message: %s", message->getIdentifier());
 
         if (DSPSignalNotification::match(*message))
         {
             DSPSignalNotification* notif = (DSPSignalNotification*) message;
             m_sampleRate = notif->getSampleRate();
             m_deviceCenterFrequency = notif->getCenterFrequency();
-            qDebug("FCDProGui::handleDSPMessages: SampleRate:%d, CenterFrequency:%llu", notif->getSampleRate(), notif->getCenterFrequency());
+            qDebug("FCDProGui::handleInputMessages: DSPSignalNotification: SampleRate:%d, CenterFrequency:%llu", notif->getSampleRate(), notif->getCenterFrequency());
             updateSampleRateAndFrequency();
 
             delete message;
diff --git a/plugins/samplesource/fcdpro/fcdprogui.h b/plugins/samplesource/fcdpro/fcdprogui.h
index fa371b5e6..8d93580f3 100644
--- a/plugins/samplesource/fcdpro/fcdprogui.h
+++ b/plugins/samplesource/fcdpro/fcdprogui.h
@@ -70,7 +70,7 @@ private:
 	void updateSampleRateAndFrequency();
 
 private slots:
-    void handleDSPMessages();
+    void handleInputMessages();
 	void on_centerFrequency_changed(quint64 value);
 	void on_ppm_valueChanged(int value);
 	void on_dcOffset_toggled(bool checked);
diff --git a/plugins/samplesource/fcdproplus/fcdproplusgui.cpp b/plugins/samplesource/fcdproplus/fcdproplusgui.cpp
index cc1495186..1d2c56798 100644
--- a/plugins/samplesource/fcdproplus/fcdproplusgui.cpp
+++ b/plugins/samplesource/fcdproplus/fcdproplusgui.cpp
@@ -60,7 +60,7 @@ FCDProPlusGui::FCDProPlusGui(DeviceSourceAPI *deviceAPI, QWidget* parent) :
 
 	displaySettings();
 
-    connect(m_deviceAPI->getDeviceEngineOutputMessageQueue(), SIGNAL(messageEnqueued()), this, SLOT(handleDSPMessages()), Qt::QueuedConnection);
+	connect(&m_inputMessageQueue, SIGNAL(messageEnqueued()), this, SLOT(handleInputMessages()), Qt::QueuedConnection);
 }
 
 FCDProPlusGui::~FCDProPlusGui()
@@ -127,20 +127,20 @@ bool FCDProPlusGui::handleMessage(const Message& message __attribute__((unused))
 	return false;
 }
 
-void FCDProPlusGui::handleDSPMessages()
+void FCDProPlusGui::handleInputMessages()
 {
     Message* message;
 
-    while ((message = m_deviceAPI->getDeviceEngineOutputMessageQueue()->pop()) != 0)
+    while ((message = m_inputMessageQueue.pop()) != 0)
     {
-        qDebug("RTLSDRGui::handleDSPMessages: message: %s", message->getIdentifier());
+        qDebug("RTLSDRGui::handleInputMessages: message: %s", message->getIdentifier());
 
         if (DSPSignalNotification::match(*message))
         {
             DSPSignalNotification* notif = (DSPSignalNotification*) message;
             m_sampleRate = notif->getSampleRate();
             m_deviceCenterFrequency = notif->getCenterFrequency();
-            qDebug("RTLSDRGui::handleDSPMessages: SampleRate:%d, CenterFrequency:%llu", notif->getSampleRate(), notif->getCenterFrequency());
+            qDebug("RTLSDRGui::handleInputMessages: DSPSignalNotification: SampleRate:%d, CenterFrequency:%llu", notif->getSampleRate(), notif->getCenterFrequency());
             updateSampleRateAndFrequency();
 
             delete message;
diff --git a/plugins/samplesource/fcdproplus/fcdproplusgui.h b/plugins/samplesource/fcdproplus/fcdproplusgui.h
index 2a6d68b20..8628df0af 100644
--- a/plugins/samplesource/fcdproplus/fcdproplusgui.h
+++ b/plugins/samplesource/fcdproplus/fcdproplusgui.h
@@ -69,7 +69,7 @@ private:
 	void updateSampleRateAndFrequency();
 
 private slots:
-    void handleDSPMessages();
+    void handleInputMessages();
 	void on_centerFrequency_changed(quint64 value);
 	void on_dcOffset_toggled(bool checked);
 	void on_iqImbalance_toggled(bool checked);
diff --git a/plugins/samplesource/filesource/filesourcegui.cpp b/plugins/samplesource/filesource/filesourcegui.cpp
index 1ff550c25..712a63b66 100644
--- a/plugins/samplesource/filesource/filesourcegui.cpp
+++ b/plugins/samplesource/filesource/filesourcegui.cpp
@@ -67,9 +67,8 @@ FileSourceGui::FileSourceGui(DeviceSourceAPI *deviceAPI, QWidget* parent) :
 	ui->playLoop->setEnabled(false);
 
     m_sampleSource = m_deviceAPI->getSampleSource();
-	connect(m_sampleSource->getOutputMessageQueueToGUI(), SIGNAL(messageEnqueued()), this, SLOT(handleSourceMessages()));
 
-    connect(m_deviceAPI->getDeviceEngineOutputMessageQueue(), SIGNAL(messageEnqueued()), this, SLOT(handleDSPMessages()), Qt::QueuedConnection);
+    connect(&m_inputMessageQueue, SIGNAL(messageEnqueued()), this, SLOT(handleInputMessages()), Qt::QueuedConnection);
 }
 
 FileSourceGui::~FileSourceGui()
@@ -128,24 +127,31 @@ bool FileSourceGui::deserialize(const QByteArray& data)
 	}
 }
 
-void FileSourceGui::handleDSPMessages()
+void FileSourceGui::handleInputMessages()
 {
     Message* message;
 
-    while ((message = m_deviceAPI->getDeviceEngineOutputMessageQueue()->pop()) != 0)
+    while ((message = m_inputMessageQueue.pop()) != 0)
     {
-        qDebug("FileSourceGui::handleDSPMessages: message: %s", message->getIdentifier());
+        qDebug("FileSourceGui::handleInputMessages: message: %s", message->getIdentifier());
 
         if (DSPSignalNotification::match(*message))
         {
             DSPSignalNotification* notif = (DSPSignalNotification*) message;
             m_deviceSampleRate = notif->getSampleRate();
             m_deviceCenterFrequency = notif->getCenterFrequency();
-            qDebug("FileSourceGui::handleDSPMessages: SampleRate:%d, CenterFrequency:%llu", notif->getSampleRate(), notif->getCenterFrequency());
+            qDebug("FileSourceGui::handleInputMessages: DSPSignalNotification: SampleRate:%d, CenterFrequency:%llu", notif->getSampleRate(), notif->getCenterFrequency());
             updateSampleRateAndFrequency();
 
             delete message;
         }
+        else
+        {
+            if (handleMessage(*message))
+            {
+                delete message;
+            }
+        }
     }
 }
 
@@ -178,21 +184,6 @@ bool FileSourceGui::handleMessage(const Message& message)
 	}
 }
 
-void FileSourceGui::handleSourceMessages()
-{
-	Message* message;
-
-	while ((message = m_sampleSource->getOutputMessageQueueToGUI()->pop()) != 0)
-	{
-		//qDebug("FileSourceGui::handleSourceMessages: message: %s", message->getIdentifier());
-
-		if (handleMessage(*message))
-		{
-			delete message;
-		}
-	}
-}
-
 void FileSourceGui::updateSampleRateAndFrequency()
 {
     m_deviceAPI->getSpectrum()->setSampleRate(m_deviceSampleRate);
diff --git a/plugins/samplesource/filesource/filesourcegui.h b/plugins/samplesource/filesource/filesourcegui.h
index 4f8aaf414..5b706ecd8 100644
--- a/plugins/samplesource/filesource/filesourcegui.h
+++ b/plugins/samplesource/filesource/filesourcegui.h
@@ -82,8 +82,7 @@ private:
 	void updateWithStreamTime();
 
 private slots:
-    void handleDSPMessages();
-	void handleSourceMessages();
+    void handleInputMessages();
 	void on_startStop_toggled(bool checked);
 	void on_playLoop_toggled(bool checked);
 	void on_play_toggled(bool checked);
diff --git a/plugins/samplesource/filesource/filesourceinput.cpp b/plugins/samplesource/filesource/filesourceinput.cpp
index 41ba249a9..a5738d48f 100644
--- a/plugins/samplesource/filesource/filesourceinput.cpp
+++ b/plugins/samplesource/filesource/filesourceinput.cpp
@@ -128,7 +128,10 @@ void FileSourceInput::openFileStream()
 			m_centerFrequency,
 			m_startingTimeStamp,
 			m_recordLength); // file stream data
-	getOutputMessageQueueToGUI()->push(report);
+
+	if (getMessageQueueToGUI()) {
+	    getMessageQueueToGUI()->push(report);
+	}
 }
 
 void FileSourceInput::seekFileStream(int seekPercentage)
@@ -178,7 +181,10 @@ bool FileSourceInput::start()
 	qDebug("FileSourceInput::startInput: started");
 
 	MsgReportFileSourceAcquisition *report = MsgReportFileSourceAcquisition::create(true); // acquisition on
-	getOutputMessageQueueToGUI()->push(report);
+
+	if (getMessageQueueToGUI()) {
+        getMessageQueueToGUI()->push(report);
+	}
 
 	return true;
 }
@@ -198,7 +204,10 @@ void FileSourceInput::stop()
 	m_deviceDescription.clear();
 
 	MsgReportFileSourceAcquisition *report = MsgReportFileSourceAcquisition::create(false); // acquisition off
-	getOutputMessageQueueToGUI()->push(report);
+
+	if (getMessageQueueToGUI()) {
+        getMessageQueueToGUI()->push(report);
+	}
 }
 
 const QString& FileSourceInput::getDeviceDescription() const
@@ -268,7 +277,10 @@ bool FileSourceInput::handleMessage(const Message& message)
 		if (m_fileSourceThread != 0)
 		{
 			report = MsgReportFileSourceStreamTiming::create(m_fileSourceThread->getSamplesCount());
-			getOutputMessageQueueToGUI()->push(report);
+
+			if (getMessageQueueToGUI()) {
+                getMessageQueueToGUI()->push(report);
+			}
 		}
 
 		return true;
diff --git a/plugins/samplesource/hackrfinput/hackrfinputgui.cpp b/plugins/samplesource/hackrfinput/hackrfinputgui.cpp
index d02988959..f417219a1 100644
--- a/plugins/samplesource/hackrfinput/hackrfinputgui.cpp
+++ b/plugins/samplesource/hackrfinput/hackrfinputgui.cpp
@@ -56,7 +56,7 @@ HackRFInputGui::HackRFInputGui(DeviceSourceAPI *deviceAPI, QWidget* parent) :
 	displaySettings();
 	displayBandwidths();
 
-    connect(m_deviceAPI->getDeviceEngineOutputMessageQueue(), SIGNAL(messageEnqueued()), this, SLOT(handleDSPMessages()), Qt::QueuedConnection);
+	connect(&m_inputMessageQueue, SIGNAL(messageEnqueued()), this, SLOT(handleInputMessages()), Qt::QueuedConnection);
 
     sendSettings();
 }
@@ -134,24 +134,31 @@ bool HackRFInputGui::handleMessage(const Message& message)
     }
 }
 
-void HackRFInputGui::handleDSPMessages()
+void HackRFInputGui::handleInputMessages()
 {
     Message* message;
 
-    while ((message = m_deviceAPI->getDeviceEngineOutputMessageQueue()->pop()) != 0)
+    while ((message = m_inputMessageQueue.pop()) != 0)
     {
-        qDebug("HackRFGui::handleDSPMessages: message: %s", message->getIdentifier());
+        qDebug("HackRFGui::handleInputMessages: message: %s", message->getIdentifier());
 
         if (DSPSignalNotification::match(*message))
         {
             DSPSignalNotification* notif = (DSPSignalNotification*) message;
             m_sampleRate = notif->getSampleRate();
             m_deviceCenterFrequency = notif->getCenterFrequency();
-            qDebug("HackRFGui::handleDSPMessages: SampleRate:%d, CenterFrequency:%llu", notif->getSampleRate(), notif->getCenterFrequency());
+            qDebug("HackRFGui::handleInputMessages: DSPSignalNotification: SampleRate:%d, CenterFrequency:%llu", notif->getSampleRate(), notif->getCenterFrequency());
             updateSampleRateAndFrequency();
 
             delete message;
         }
+        else
+        {
+            if (handleMessage(*message))
+            {
+                delete message;
+            }
+        }
     }
 }
 
diff --git a/plugins/samplesource/hackrfinput/hackrfinputgui.h b/plugins/samplesource/hackrfinput/hackrfinputgui.h
index 08f9e5cc7..6370ee2e7 100644
--- a/plugins/samplesource/hackrfinput/hackrfinputgui.h
+++ b/plugins/samplesource/hackrfinput/hackrfinputgui.h
@@ -80,7 +80,7 @@ private:
     void updateSampleRateAndFrequency();
 
 private slots:
-    void handleDSPMessages();
+    void handleInputMessages();
 	void on_centerFrequency_changed(quint64 value);
 	void on_sampleRate_changed(quint64 value);
 	void on_LOppm_valueChanged(int value);
diff --git a/plugins/samplesource/limesdrinput/limesdrinputgui.cpp b/plugins/samplesource/limesdrinput/limesdrinputgui.cpp
index f56c7e4a1..35b08d705 100644
--- a/plugins/samplesource/limesdrinput/limesdrinputgui.cpp
+++ b/plugins/samplesource/limesdrinput/limesdrinputgui.cpp
@@ -75,7 +75,7 @@ LimeSDRInputGUI::LimeSDRInputGUI(DeviceSourceAPI *deviceAPI, QWidget* parent) :
 
     displaySettings();
 
-    connect(m_deviceAPI->getDeviceEngineOutputMessageQueue(), SIGNAL(messageEnqueued()), this, SLOT(handleMessagesToGUI()), Qt::QueuedConnection);
+    connect(&m_inputMessageQueue, SIGNAL(messageEnqueued()), this, SLOT(handleInputMessages()), Qt::QueuedConnection);
 }
 
 LimeSDRInputGUI::~LimeSDRInputGUI()
@@ -142,26 +142,26 @@ bool LimeSDRInputGUI::handleMessage(const Message& message __attribute__((unused
     return false;
 }
 
-void LimeSDRInputGUI::handleMessagesToGUI()
+void LimeSDRInputGUI::handleInputMessages()
 {
     Message* message;
 
-    while ((message = m_deviceAPI->getDeviceEngineOutputMessageQueue()->pop()) != 0)
+    while ((message = m_inputMessageQueue.pop()) != 0)
     {
+        qDebug("LimeSDRInputGUI::handleInputMessages: message: %s", message->getIdentifier());
+
         if (DSPSignalNotification::match(*message))
         {
-            qDebug("LimeSDRInputGUI::handleMessagesToGUI: message: %s", message->getIdentifier());
             DSPSignalNotification* notif = (DSPSignalNotification*) message;
             m_sampleRate = notif->getSampleRate();
             m_deviceCenterFrequency = notif->getCenterFrequency();
-            qDebug("LimeSDRInputGUI::handleMessagesToGUI: SampleRate: %d, CenterFrequency: %llu", notif->getSampleRate(), notif->getCenterFrequency());
+            qDebug("LimeSDRInputGUI::handleInputMessages: DSPSignalNotification: SampleRate: %d, CenterFrequency: %llu", notif->getSampleRate(), notif->getCenterFrequency());
             updateSampleRateAndFrequency();
 
             delete message;
         }
         else if (LimeSDRInput::MsgReportLimeSDRToGUI::match(*message))
         {
-            qDebug("LimeSDRInputGUI::handleMessagesToGUI: message: %s", message->getIdentifier());
             LimeSDRInput::MsgReportLimeSDRToGUI *report = (LimeSDRInput::MsgReportLimeSDRToGUI *) message;
 
             m_settings.m_centerFrequency = report->getCenterFrequency();
@@ -173,7 +173,7 @@ void LimeSDRInputGUI::handleMessagesToGUI()
             blockApplySettings(false);
 
             LimeSDRInput::MsgSetReferenceConfig* conf = LimeSDRInput::MsgSetReferenceConfig::create(m_settings);
-            m_sampleSource->getInputMessageQueue()->push(conf);
+            m_sampleSource->getInputMessageQueue()->push(conf); // TODO: remove from here should be done device to device
 
             delete message;
         }
diff --git a/plugins/samplesource/limesdrinput/limesdrinputgui.h b/plugins/samplesource/limesdrinput/limesdrinputgui.h
index 0277e11e7..c950bd751 100644
--- a/plugins/samplesource/limesdrinput/limesdrinputgui.h
+++ b/plugins/samplesource/limesdrinput/limesdrinputgui.h
@@ -75,8 +75,7 @@ private:
     void blockApplySettings(bool block);
 
 private slots:
-    void handleMessagesToGUI();
-
+    void handleInputMessages();
     void on_startStop_toggled(bool checked);
     void on_record_toggled(bool checked);
     void on_centerFrequency_changed(quint64 value);
diff --git a/plugins/samplesource/plutosdrinput/plutosdrinputgui.cpp b/plugins/samplesource/plutosdrinput/plutosdrinputgui.cpp
index 4415a5b8c..809e042f8 100644
--- a/plugins/samplesource/plutosdrinput/plutosdrinputgui.cpp
+++ b/plugins/samplesource/plutosdrinput/plutosdrinputgui.cpp
@@ -66,7 +66,7 @@ PlutoSDRInputGui::PlutoSDRInputGui(DeviceSourceAPI *deviceAPI, QWidget* parent)
     connect(&m_statusTimer, SIGNAL(timeout()), this, SLOT(updateStatus()));
     m_statusTimer.start(500);
 
-    connect(m_deviceAPI->getDeviceEngineOutputMessageQueue(), SIGNAL(messageEnqueued()), this, SLOT(handleDSPMessages()), Qt::QueuedConnection);
+    connect(&m_inputMessageQueue, SIGNAL(messageEnqueued()), this, SLOT(handleInputMessages()), Qt::QueuedConnection);
 }
 
 PlutoSDRInputGui::~PlutoSDRInputGui()
@@ -385,24 +385,32 @@ void PlutoSDRInputGui::setSampleRateLimits()
     ui->sampleRate->setValue(m_settings.m_devSampleRate);
 }
 
-void PlutoSDRInputGui::handleDSPMessages()
+void PlutoSDRInputGui::handleInputMessages()
 {
     Message* message;
 
-    while ((message = m_deviceAPI->getDeviceEngineOutputMessageQueue()->pop()) != 0)
+    while ((message = m_inputMessageQueue.pop()) != 0)
     {
+        qDebug("LimeSDRInputGUI::handleInputMessages: message: %s", message->getIdentifier());
+
         if (DSPSignalNotification::match(*message))
         {
-            qDebug("LimeSDRInputGUI::handleMessagesToGUI: message: %s", message->getIdentifier());
             DSPSignalNotification* notif = (DSPSignalNotification*) message;
             m_sampleRate = notif->getSampleRate();
             m_deviceCenterFrequency = notif->getCenterFrequency();
-            qDebug("LimeSDRInputGUI::handleMessagesToGUI: SampleRate: %d, CenterFrequency: %llu", notif->getSampleRate(), notif->getCenterFrequency());
+            qDebug("LimeSDRInputGUI::handleInputMessages: DSPSignalNotification: SampleRate: %d, CenterFrequency: %llu", notif->getSampleRate(), notif->getCenterFrequency());
             updateSampleRateAndFrequency();
             setFIRBWLimits();
 
             delete message;
         }
+        else
+        {
+            if (handleMessage(*message))
+            {
+                delete message;
+            }
+        }
     }
 }
 
diff --git a/plugins/samplesource/plutosdrinput/plutosdrinputgui.h b/plugins/samplesource/plutosdrinput/plutosdrinputgui.h
index dd865e398..20c62ac04 100644
--- a/plugins/samplesource/plutosdrinput/plutosdrinputgui.h
+++ b/plugins/samplesource/plutosdrinput/plutosdrinputgui.h
@@ -93,7 +93,7 @@ private slots:
     void on_antenna_currentIndexChanged(int index);
     void updateHardware();
     void updateStatus();
-    void handleDSPMessages();
+    void handleInputMessages();
 };
 
 #endif /* PLUGINS_SAMPLESOURCE_PLUTOSDRINPUT_PLUTOSDRINPUTGUI_H_ */
diff --git a/plugins/samplesource/rtlsdr/rtlsdrgui.cpp b/plugins/samplesource/rtlsdr/rtlsdrgui.cpp
index 449dd9328..fd06f4887 100644
--- a/plugins/samplesource/rtlsdr/rtlsdrgui.cpp
+++ b/plugins/samplesource/rtlsdr/rtlsdrgui.cpp
@@ -51,8 +51,7 @@ RTLSDRGui::RTLSDRGui(DeviceSourceAPI *deviceAPI, QWidget* parent) :
 
 	displaySettings();
 
-	connect(m_sampleSource->getOutputMessageQueueToGUI(), SIGNAL(messageEnqueued()), this, SLOT(handleSourceMessages()));
-    connect(m_deviceAPI->getDeviceEngineOutputMessageQueue(), SIGNAL(messageEnqueued()), this, SLOT(handleDSPMessages()), Qt::QueuedConnection);
+	connect(&m_inputMessageQueue, SIGNAL(messageEnqueued()), this, SLOT(handleInputMessages()), Qt::QueuedConnection);
 
     queryDeviceReport(); // will reply with MsgReportRTLSDR to report gain list
 }
@@ -144,42 +143,34 @@ bool RTLSDRGui::handleMessage(const Message& message)
 	}
 }
 
-void RTLSDRGui::handleDSPMessages()
+void RTLSDRGui::handleInputMessages()
 {
     Message* message;
 
-    while ((message = m_deviceAPI->getDeviceEngineOutputMessageQueue()->pop()) != 0)
+    while ((message = m_inputMessageQueue.pop()) != 0)
     {
-        qDebug("RTLSDRGui::handleDSPMessages: message: %s", message->getIdentifier());
+        qDebug("RTLSDRGui::handleInputMessages: message: %s", message->getIdentifier());
 
         if (DSPSignalNotification::match(*message))
         {
             DSPSignalNotification* notif = (DSPSignalNotification*) message;
             m_sampleRate = notif->getSampleRate();
             m_deviceCenterFrequency = notif->getCenterFrequency();
-            qDebug("RTLSDRGui::handleDSPMessages: SampleRate:%d, CenterFrequency:%llu", notif->getSampleRate(), notif->getCenterFrequency());
+            qDebug("RTLSDRGui::handleInputMessages: DSPSignalNotification: SampleRate:%d, CenterFrequency:%llu", notif->getSampleRate(), notif->getCenterFrequency());
             updateSampleRateAndFrequency();
 
             delete message;
         }
+        else
+        {
+            if (handleMessage(*message))
+            {
+                delete message;
+            }
+        }
     }
 }
 
-void RTLSDRGui::handleSourceMessages()
-{
-	Message* message;
-
-	while ((message = m_sampleSource->getOutputMessageQueueToGUI()->pop()) != 0)
-	{
-		qDebug("RTLSDRGui::HandleSourceMessages: message: %s", message->getIdentifier());
-
-		if (handleMessage(*message))
-		{
-			delete message;
-		}
-	}
-}
-
 void RTLSDRGui::updateSampleRateAndFrequency()
 {
     m_deviceAPI->getSpectrum()->setSampleRate(m_sampleRate);
diff --git a/plugins/samplesource/rtlsdr/rtlsdrgui.h b/plugins/samplesource/rtlsdr/rtlsdrgui.h
index 62aea490c..5575a31df 100644
--- a/plugins/samplesource/rtlsdr/rtlsdrgui.h
+++ b/plugins/samplesource/rtlsdr/rtlsdrgui.h
@@ -72,7 +72,7 @@ private:
 	void updateSampleRateAndFrequency();
 
 private slots:
-    void handleDSPMessages();
+    void handleInputMessages();
 	void on_centerFrequency_changed(quint64 value);
 	void on_sampleRate_changed(quint64 value);
 	void on_lowSampleRate_toggled(bool checked);
@@ -89,7 +89,6 @@ private slots:
     void on_record_toggled(bool checked);
 	void updateHardware();
 	void updateStatus();
-	void handleSourceMessages();
 };
 
 #endif // INCLUDE_RTLSDRGUI_H
diff --git a/plugins/samplesource/rtlsdr/rtlsdrinput.cpp b/plugins/samplesource/rtlsdr/rtlsdrinput.cpp
index 76d61af94..e1feecf62 100644
--- a/plugins/samplesource/rtlsdr/rtlsdrinput.cpp
+++ b/plugins/samplesource/rtlsdr/rtlsdrinput.cpp
@@ -256,7 +256,10 @@ bool RTLSDRInput::handleMessage(const Message& message)
         qDebug() << "RTLSDRInput::handleMessage: MsgQueryRTLSDR";
 
         MsgReportRTLSDR *message = MsgReportRTLSDR::create(m_gains);
-        getOutputMessageQueueToGUI()->push(message);
+
+        if (getMessageQueueToGUI()) {
+            getMessageQueueToGUI()->push(message);
+        }
 
         return true;
     }
diff --git a/plugins/samplesource/sdrdaemonsource/sdrdaemonsourcegui.cpp b/plugins/samplesource/sdrdaemonsource/sdrdaemonsourcegui.cpp
index 608d4b022..34eb57b7b 100644
--- a/plugins/samplesource/sdrdaemonsource/sdrdaemonsourcegui.cpp
+++ b/plugins/samplesource/sdrdaemonsource/sdrdaemonsourcegui.cpp
@@ -103,11 +103,10 @@ SDRdaemonSourceGui::SDRdaemonSourceGui(DeviceSourceAPI *deviceAPI, QWidget* pare
     connect(&m_updateTimer, SIGNAL(timeout()), this, SLOT(updateHardware()));
 
     m_sampleSource = (SDRdaemonSourceInput*) m_deviceAPI->getSampleSource();
-	connect(m_sampleSource->getOutputMessageQueueToGUI(), SIGNAL(messageEnqueued()), this, SLOT(handleSourceMessages()));
 
 	displaySettings();
 
-    connect(m_deviceAPI->getDeviceEngineOutputMessageQueue(), SIGNAL(messageEnqueued()), this, SLOT(handleDSPMessages()), Qt::QueuedConnection);
+	connect(&m_inputMessageQueue, SIGNAL(messageEnqueued()), this, SLOT(handleInputMessages()), Qt::QueuedConnection);
 
     m_eventsTime.start();
     displayEventCounts();
@@ -253,44 +252,36 @@ bool SDRdaemonSourceGui::handleMessage(const Message& message)
 	}
 }
 
-void SDRdaemonSourceGui::handleDSPMessages()
+void SDRdaemonSourceGui::handleInputMessages()
 {
     Message* message;
 
-    while ((message = m_deviceAPI->getDeviceEngineOutputMessageQueue()->pop()) != 0)
+    while ((message = m_inputMessageQueue.pop()) != 0)
     {
-        qDebug("SDRdaemonGui::handleDSPMessages: message: %s", message->getIdentifier());
+        qDebug("SDRdaemonGui::handleInputMessages: message: %s", message->getIdentifier());
 
         if (DSPSignalNotification::match(*message))
         {
             DSPSignalNotification* notif = (DSPSignalNotification*) message;
             m_deviceSampleRate = notif->getSampleRate();
             m_deviceCenterFrequency = notif->getCenterFrequency();
-            qDebug("SDRdaemonGui::handleDSPMessages: SampleRate:%d, CenterFrequency:%llu", notif->getSampleRate(), notif->getCenterFrequency());
+            qDebug("SDRdaemonGui::handleInputMessages: DSPSignalNotification: SampleRate:%d, CenterFrequency:%llu", notif->getSampleRate(), notif->getCenterFrequency());
             updateSampleRateAndFrequency();
             DSPSignalNotification *fwd = new DSPSignalNotification(*notif);
             m_sampleSource->getInputMessageQueue()->push(fwd);
 
             delete message;
         }
+        else
+        {
+            if (handleMessage(*message))
+            {
+                delete message;
+            }
+        }
     }
 }
 
-void SDRdaemonSourceGui::handleSourceMessages()
-{
-	Message* message;
-
-	while ((message = m_sampleSource->getOutputMessageQueueToGUI()->pop()) != 0)
-	{
-		//qDebug("SDRdaemonGui::handleSourceMessages: message: %s", message->getIdentifier());
-
-		if (handleMessage(*message))
-		{
-			delete message;
-		}
-	}
-}
-
 void SDRdaemonSourceGui::updateSampleRateAndFrequency()
 {
     m_deviceAPI->getSpectrum()->setSampleRate(m_deviceSampleRate);
diff --git a/plugins/samplesource/sdrdaemonsource/sdrdaemonsourcegui.h b/plugins/samplesource/sdrdaemonsource/sdrdaemonsourcegui.h
index 3f5fae5cd..44cbaf9c4 100644
--- a/plugins/samplesource/sdrdaemonsource/sdrdaemonsourcegui.h
+++ b/plugins/samplesource/sdrdaemonsource/sdrdaemonsourcegui.h
@@ -124,8 +124,7 @@ private:
     void displayEventTimer();
 
 private slots:
-    void handleDSPMessages();
-	void handleSourceMessages();
+    void handleInputMessages();
 	void on_applyButton_clicked(bool checked);
 	void on_dcOffset_toggled(bool checked);
 	void on_iqImbalance_toggled(bool checked);
diff --git a/plugins/samplesource/sdrdaemonsource/sdrdaemonsourceinput.cpp b/plugins/samplesource/sdrdaemonsource/sdrdaemonsourceinput.cpp
index 2b88f86fe..3f725d439 100644
--- a/plugins/samplesource/sdrdaemonsource/sdrdaemonsourceinput.cpp
+++ b/plugins/samplesource/sdrdaemonsource/sdrdaemonsourceinput.cpp
@@ -52,7 +52,7 @@ SDRdaemonSourceInput::SDRdaemonSourceInput(DeviceSourceAPI *deviceAPI) :
     m_autoCorrBuffer(false)
 {
 	m_sampleFifo.setSize(96000 * 4);
-	m_SDRdaemonUDPHandler = new SDRdaemonSourceUDPHandler(&m_sampleFifo, getOutputMessageQueueToGUI(), m_deviceAPI);
+	m_SDRdaemonUDPHandler = new SDRdaemonSourceUDPHandler(&m_sampleFifo, getMessageQueueToGUI(), m_deviceAPI);
 	m_SDRdaemonUDPHandler->connectTimer(&m_masterTimer);
 
     char recFileNameCStr[30];
@@ -181,3 +181,9 @@ bool SDRdaemonSourceInput::handleMessage(const Message& message)
 	}
 }
 
+void SDRdaemonSourceInput::setMessageQueueToGUI(MessageQueue *queue)
+{
+    DeviceSampleSource::setMessageQueueToGUI(queue);
+    m_SDRdaemonUDPHandler->setMessageQueueToGUI(queue);
+}
+
diff --git a/plugins/samplesource/sdrdaemonsource/sdrdaemonsourceinput.h b/plugins/samplesource/sdrdaemonsource/sdrdaemonsourceinput.h
index 91de78fc8..e74f9fb1f 100644
--- a/plugins/samplesource/sdrdaemonsource/sdrdaemonsourceinput.h
+++ b/plugins/samplesource/sdrdaemonsource/sdrdaemonsourceinput.h
@@ -318,6 +318,8 @@ public:
 
 	virtual bool handleMessage(const Message& message);
 
+	void setMessageQueueToGUI(MessageQueue *queue);
+
 private:
 	DeviceSourceAPI *m_deviceAPI;
 	QMutex m_mutex;
diff --git a/plugins/samplesource/sdrdaemonsource/sdrdaemonsourceudphandler.cpp b/plugins/samplesource/sdrdaemonsource/sdrdaemonsourceudphandler.cpp
index 2e3e8e8fb..f84f280c2 100644
--- a/plugins/samplesource/sdrdaemonsource/sdrdaemonsourceudphandler.cpp
+++ b/plugins/samplesource/sdrdaemonsource/sdrdaemonsourceudphandler.cpp
@@ -179,7 +179,10 @@ void SDRdaemonSourceUDPHandler::processData()
             m_centerFrequency * 1000, // Frequency in Hz for the GUI
             m_tv_sec,
             m_tv_usec);
-        m_outputMessageQueueToGUI->push(report);
+
+        if (m_outputMessageQueueToGUI) {
+            m_outputMessageQueueToGUI->push(report);
+        }
     }
 }
 
@@ -258,6 +261,9 @@ void SDRdaemonSourceUDPHandler::tick()
             m_sdrDaemonBuffer.getAvgNbRecovery(),
             nbOriginalBlocks,
             nbFECblocks);
-            m_outputMessageQueueToGUI->push(report);
+
+		    if (m_outputMessageQueueToGUI) {
+                m_outputMessageQueueToGUI->push(report);
+		    }
 	}
 }
diff --git a/plugins/samplesource/sdrdaemonsource/sdrdaemonsourceudphandler.h b/plugins/samplesource/sdrdaemonsource/sdrdaemonsourceudphandler.h
index 3513841c9..47cf5689f 100644
--- a/plugins/samplesource/sdrdaemonsource/sdrdaemonsourceudphandler.h
+++ b/plugins/samplesource/sdrdaemonsource/sdrdaemonsourceudphandler.h
@@ -38,6 +38,7 @@ class SDRdaemonSourceUDPHandler : public QObject
 public:
 	SDRdaemonSourceUDPHandler(SampleSinkFifo* sampleFifo, MessageQueue *outputMessageQueueToGUI, DeviceSourceAPI *deviceAPI);
 	~SDRdaemonSourceUDPHandler();
+	void setMessageQueueToGUI(MessageQueue *queue) { m_outputMessageQueueToGUI = queue; }
 	void connectTimer(const QTimer* timer);
 	void start();
 	void stop();
diff --git a/plugins/samplesource/sdrplay/sdrplaygui.cpp b/plugins/samplesource/sdrplay/sdrplaygui.cpp
index 926f0dd8d..11365daf3 100644
--- a/plugins/samplesource/sdrplay/sdrplaygui.cpp
+++ b/plugins/samplesource/sdrplay/sdrplaygui.cpp
@@ -69,9 +69,7 @@ SDRPlayGui::SDRPlayGui(DeviceSourceAPI *deviceAPI, QWidget* parent) :
 
     displaySettings();
 
-//    connect(m_sampleSource->getOutputMessageQueueToGUI(), SIGNAL(messageEnqueued()), this, SLOT(handleSourceMessages()));
-//    connect(m_deviceAPI->getDeviceEngineOutputMessageQueue(), SIGNAL(messageEnqueued()), this, SLOT(handleDSPMessages()), Qt::QueuedConnection);
-    connect(&m_inputMessageQueue, SIGNAL(messageEnqueued()), this, SLOT(handleInputMessages()));
+    connect(&m_inputMessageQueue, SIGNAL(messageEnqueued()), this, SLOT(handleInputMessages()), Qt::QueuedConnection);
 }
 
 SDRPlayGui::~SDRPlayGui()
diff --git a/plugins/samplesource/sdrplay/sdrplayinput.cpp b/plugins/samplesource/sdrplay/sdrplayinput.cpp
index a63965147..9e1224d36 100644
--- a/plugins/samplesource/sdrplay/sdrplayinput.cpp
+++ b/plugins/samplesource/sdrplay/sdrplayinput.cpp
@@ -319,7 +319,9 @@ bool SDRPlayInput::applySettings(const SDRPlaySettings& settings, bool forwardCh
                             mirisdr_get_tuner_gain(m_dev)
                     );
 
-                    getOutputMessageQueueToGUI()->push(message);
+                    if (getMessageQueueToGUI()) {
+                        getMessageQueueToGUI()->push(message);
+                    }
                 }
             }
         }
@@ -418,7 +420,10 @@ bool SDRPlayInput::applySettings(const SDRPlaySettings& settings, bool forwardCh
                     mirisdr_get_baseband_gain(m_dev),
                     mirisdr_get_tuner_gain(m_dev)
             );
-            getOutputMessageQueueToGUI()->push(message);
+
+            if (getMessageQueueToGUI()) {
+                getMessageQueueToGUI()->push(message);
+            }
         }
     }
 
diff --git a/sdrbase/dsp/devicesamplesource.h b/sdrbase/dsp/devicesamplesource.h
index 15d29c900..dc04b98b3 100644
--- a/sdrbase/dsp/devicesamplesource.h
+++ b/sdrbase/dsp/devicesamplesource.h
@@ -44,7 +44,7 @@ public:
 	MessageQueue *getInputMessageQueue() { return &m_inputMessageQueue; }
 	void setMessageQueueToGUI(MessageQueue *queue) { m_guiMessageQueue = queue; }
 	MessageQueue *getMessageQueueToGUI() { return m_guiMessageQueue; }
-	MessageQueue *getOutputMessageQueueToGUI() { return &m_outputMessageQueueToGUI; } // TODO: remove
+	//MessageQueue *getOutputMessageQueueToGUI() { return &m_outputMessageQueueToGUI; } // TODO: remove
     SampleSinkFifo* getSampleFifo() { return &m_sampleFifo; }
 
 protected slots:
diff --git a/sdrbase/mainwindow.cpp b/sdrbase/mainwindow.cpp
index 128f61fbc..f552562e4 100644
--- a/sdrbase/mainwindow.cpp
+++ b/sdrbase/mainwindow.cpp
@@ -306,6 +306,7 @@ void MainWindow::removeLastDevice()
 
         // deletes old UI and input object
         m_deviceUIs.back()->m_deviceSourceAPI->freeChannels();      // destroys the channel instances
+        m_deviceUIs.back()->m_deviceSourceAPI->getSampleSource()->setMessageQueueToGUI(0); // have source stop sending messages to the GUI
         m_deviceUIs.back()->m_deviceSourceAPI->getPluginInterface()->deleteSampleSourcePluginInstanceGUI(
                 m_deviceUIs.back()->m_deviceSourceAPI->getSampleSourcePluginInstanceGUI());
         m_deviceUIs.back()->m_deviceSourceAPI->resetSampleSourceId();
@@ -844,6 +845,7 @@ void MainWindow::on_sampleSource_confirmClicked(bool checked __attribute__((unus
         deviceUI->m_deviceSourceAPI->stopAcquisition();
 
         // deletes old UI and input object
+        deviceUI->m_deviceSourceAPI->getSampleSource()->setMessageQueueToGUI(0); // have source stop sending messages to the GUI
         deviceUI->m_deviceSourceAPI->getPluginInterface()->deleteSampleSourcePluginInstanceGUI(deviceUI->m_deviceSourceAPI->getSampleSourcePluginInstanceGUI());
         deviceUI->m_deviceSourceAPI->resetSampleSourceId();
         deviceUI->m_deviceSourceAPI->clearBuddiesLists(); // clear old API buddies lists