diff --git a/plugins/samplesink/bladerfoutput/bladerfoutput.h b/plugins/samplesink/bladerfoutput/bladerfoutput.h
index 03c44020e..c668575cd 100644
--- a/plugins/samplesink/bladerfoutput/bladerfoutput.h
+++ b/plugins/samplesink/bladerfoutput/bladerfoutput.h
@@ -97,6 +97,7 @@ public:
 	virtual bool start();
 	virtual void stop();
 
+    virtual void setMessageQueueToGUI(MessageQueue *queue) { m_guiMessageQueue = queue; }
 	virtual const QString& getDeviceDescription() const;
 	virtual int getSampleRate() const;
 	virtual quint64 getCenterFrequency() const;
diff --git a/plugins/samplesink/filesink/filesinkoutput.h b/plugins/samplesink/filesink/filesinkoutput.h
index afecc5ddd..3117f4b3d 100644
--- a/plugins/samplesink/filesink/filesinkoutput.h
+++ b/plugins/samplesink/filesink/filesinkoutput.h
@@ -177,6 +177,7 @@ public:
 	virtual bool start();
 	virtual void stop();
 
+    virtual void setMessageQueueToGUI(MessageQueue *queue) { m_guiMessageQueue = queue; }
 	virtual const QString& getDeviceDescription() const;
 	virtual int getSampleRate() const;
 	virtual quint64 getCenterFrequency() const;
diff --git a/plugins/samplesink/hackrfoutput/hackrfoutput.h b/plugins/samplesink/hackrfoutput/hackrfoutput.h
index c18370530..c2e9bb30f 100644
--- a/plugins/samplesink/hackrfoutput/hackrfoutput.h
+++ b/plugins/samplesink/hackrfoutput/hackrfoutput.h
@@ -97,6 +97,7 @@ public:
 	virtual bool start();
 	virtual void stop();
 
+    virtual void setMessageQueueToGUI(MessageQueue *queue) { m_guiMessageQueue = queue; }
 	virtual const QString& getDeviceDescription() const;
 	virtual int getSampleRate() const;
 	virtual quint64 getCenterFrequency() const;
diff --git a/plugins/samplesink/limesdroutput/limesdroutput.h b/plugins/samplesink/limesdroutput/limesdroutput.h
index 82a9c0705..19571645e 100644
--- a/plugins/samplesink/limesdroutput/limesdroutput.h
+++ b/plugins/samplesink/limesdroutput/limesdroutput.h
@@ -191,6 +191,7 @@ public:
     virtual bool start();
     virtual void stop();
 
+    virtual void setMessageQueueToGUI(MessageQueue *queue) { m_guiMessageQueue = queue; }
     virtual const QString& getDeviceDescription() const;
     virtual int getSampleRate() const;
     virtual quint64 getCenterFrequency() const;
diff --git a/plugins/samplesink/plutosdroutput/plutosdroutput.h b/plugins/samplesink/plutosdroutput/plutosdroutput.h
index 037240c81..9606469a0 100644
--- a/plugins/samplesink/plutosdroutput/plutosdroutput.h
+++ b/plugins/samplesink/plutosdroutput/plutosdroutput.h
@@ -79,6 +79,7 @@ public:
     virtual bool start();
     virtual void stop();
 
+    virtual void setMessageQueueToGUI(MessageQueue *queue) { m_guiMessageQueue = queue; }
     virtual const QString& getDeviceDescription() const;
     virtual int getSampleRate() const;
     virtual quint64 getCenterFrequency() const;
diff --git a/plugins/samplesink/sdrdaemonsink/sdrdaemonsinkoutput.h b/plugins/samplesink/sdrdaemonsink/sdrdaemonsinkoutput.h
index 2aad5cac9..0be2c199d 100644
--- a/plugins/samplesink/sdrdaemonsink/sdrdaemonsinkoutput.h
+++ b/plugins/samplesink/sdrdaemonsink/sdrdaemonsinkoutput.h
@@ -158,6 +158,7 @@ public:
 	virtual bool start();
 	virtual void stop();
 
+    virtual void setMessageQueueToGUI(MessageQueue *queue) { m_guiMessageQueue = queue; }
 	virtual const QString& getDeviceDescription() const;
 	virtual int getSampleRate() const;
 	virtual quint64 getCenterFrequency() const;
diff --git a/plugins/samplesource/airspy/airspyinput.h b/plugins/samplesource/airspy/airspyinput.h
index 73a5dba7c..828ae1120 100644
--- a/plugins/samplesource/airspy/airspyinput.h
+++ b/plugins/samplesource/airspy/airspyinput.h
@@ -97,6 +97,7 @@ public:
 	virtual bool start();
 	virtual void stop();
 
+	virtual void setMessageQueueToGUI(MessageQueue *queue) { m_guiMessageQueue = queue; }
 	virtual const QString& getDeviceDescription() const;
 	virtual int getSampleRate() const;
 	virtual quint64 getCenterFrequency() const;
diff --git a/plugins/samplesource/bladerfinput/bladerfinput.h b/plugins/samplesource/bladerfinput/bladerfinput.h
index 5b464dcc2..24ee4286c 100644
--- a/plugins/samplesource/bladerfinput/bladerfinput.h
+++ b/plugins/samplesource/bladerfinput/bladerfinput.h
@@ -100,6 +100,7 @@ public:
 	virtual bool start();
 	virtual void stop();
 
+    virtual void setMessageQueueToGUI(MessageQueue *queue) { m_guiMessageQueue = queue; }
 	virtual const QString& getDeviceDescription() const;
 	virtual int getSampleRate() const;
 	virtual quint64 getCenterFrequency() const;
diff --git a/plugins/samplesource/fcdpro/fcdproinput.h b/plugins/samplesource/fcdpro/fcdproinput.h
index 248db0db0..b623e41c7 100644
--- a/plugins/samplesource/fcdpro/fcdproinput.h
+++ b/plugins/samplesource/fcdpro/fcdproinput.h
@@ -104,6 +104,7 @@ public:
 	virtual bool start();
 	virtual void stop();
 
+    virtual void setMessageQueueToGUI(MessageQueue *queue) { m_guiMessageQueue = queue; }
 	virtual const QString& getDeviceDescription() const;
 	virtual int getSampleRate() const;
 	virtual quint64 getCenterFrequency() const;
diff --git a/plugins/samplesource/fcdproplus/fcdproplusinput.h b/plugins/samplesource/fcdproplus/fcdproplusinput.h
index 46108a514..30b876afa 100644
--- a/plugins/samplesource/fcdproplus/fcdproplusinput.h
+++ b/plugins/samplesource/fcdproplus/fcdproplusinput.h
@@ -103,6 +103,7 @@ public:
 	virtual bool start();
 	virtual void stop();
 
+    virtual void setMessageQueueToGUI(MessageQueue *queue) { m_guiMessageQueue = queue; }
 	virtual const QString& getDeviceDescription() const;
 	virtual int getSampleRate() const;
 	virtual quint64 getCenterFrequency() const;
diff --git a/plugins/samplesource/filesource/filesourceinput.h b/plugins/samplesource/filesource/filesourceinput.h
index cad728555..ea5ed431c 100644
--- a/plugins/samplesource/filesource/filesourceinput.h
+++ b/plugins/samplesource/filesource/filesourceinput.h
@@ -229,6 +229,7 @@ public:
 	virtual bool start();
 	virtual void stop();
 
+    virtual void setMessageQueueToGUI(MessageQueue *queue) { m_guiMessageQueue = queue; }
 	virtual const QString& getDeviceDescription() const;
 	virtual int getSampleRate() const;
 	virtual quint64 getCenterFrequency() const;
diff --git a/plugins/samplesource/hackrfinput/hackrfinput.h b/plugins/samplesource/hackrfinput/hackrfinput.h
index 1fe08c1a0..3e603fc9a 100644
--- a/plugins/samplesource/hackrfinput/hackrfinput.h
+++ b/plugins/samplesource/hackrfinput/hackrfinput.h
@@ -117,6 +117,7 @@ public:
 	virtual bool start();
 	virtual void stop();
 
+    virtual void setMessageQueueToGUI(MessageQueue *queue) { m_guiMessageQueue = queue; }
 	virtual const QString& getDeviceDescription() const;
 	virtual int getSampleRate() const;
 	virtual quint64 getCenterFrequency() const;
diff --git a/plugins/samplesource/limesdrinput/limesdrinput.h b/plugins/samplesource/limesdrinput/limesdrinput.h
index 927280f8b..42314ef92 100644
--- a/plugins/samplesource/limesdrinput/limesdrinput.h
+++ b/plugins/samplesource/limesdrinput/limesdrinput.h
@@ -211,6 +211,7 @@ public:
     virtual bool start();
     virtual void stop();
 
+    virtual void setMessageQueueToGUI(MessageQueue *queue) { m_guiMessageQueue = queue; }
     virtual const QString& getDeviceDescription() const;
     virtual int getSampleRate() const;
     virtual quint64 getCenterFrequency() const;
diff --git a/plugins/samplesource/plutosdrinput/plutosdrinput.h b/plugins/samplesource/plutosdrinput/plutosdrinput.h
index b1132a5cd..6504418d7 100644
--- a/plugins/samplesource/plutosdrinput/plutosdrinput.h
+++ b/plugins/samplesource/plutosdrinput/plutosdrinput.h
@@ -99,6 +99,7 @@ public:
     virtual bool start();
     virtual void stop();
 
+    virtual void setMessageQueueToGUI(MessageQueue *queue) { m_guiMessageQueue = queue; }
     virtual const QString& getDeviceDescription() const;
     virtual int getSampleRate() const;
     virtual quint64 getCenterFrequency() const;
diff --git a/plugins/samplesource/rtlsdr/rtlsdrgui.cpp b/plugins/samplesource/rtlsdr/rtlsdrgui.cpp
index c200fbac6..8553eee5e 100644
--- a/plugins/samplesource/rtlsdr/rtlsdrgui.cpp
+++ b/plugins/samplesource/rtlsdr/rtlsdrgui.cpp
@@ -55,6 +55,9 @@ RTLSDRGui::RTLSDRGui(DeviceUISet *deviceUISet, QWidget* parent) :
 
 	displaySettings();
 
+	m_gains = m_sampleSource->getGains();
+	displayGains();
+
 	connect(&m_inputMessageQueue, SIGNAL(messageEnqueued()), this, SLOT(handleInputMessages()), Qt::QueuedConnection);
 }
 
@@ -133,13 +136,7 @@ bool RTLSDRGui::deserialize(const QByteArray& data)
 
 bool RTLSDRGui::handleMessage(const Message& message)
 {
-	if (RTLSDRInput::MsgReportRTLSDR::match(message))
-	{
-		m_gains = ((RTLSDRInput::MsgReportRTLSDR&) message).getGains();
-		displayGains();
-		return true;
-	}
-	else if (RTLSDRInput::MsgConfigureRTLSDR::match(message))
+	if (RTLSDRInput::MsgConfigureRTLSDR::match(message))
 	{
 	    const RTLSDRInput::MsgConfigureRTLSDR& cfg = (RTLSDRInput::MsgConfigureRTLSDR&) message;
 	    m_settings = cfg.getSettings();
diff --git a/plugins/samplesource/rtlsdr/rtlsdrgui.h b/plugins/samplesource/rtlsdr/rtlsdrgui.h
index 3693f4cab..a7d6bf37a 100644
--- a/plugins/samplesource/rtlsdr/rtlsdrgui.h
+++ b/plugins/samplesource/rtlsdr/rtlsdrgui.h
@@ -61,7 +61,7 @@ private:
 	QTimer m_updateTimer;
 	QTimer m_statusTimer;
 	std::vector<int> m_gains;
-	DeviceSampleSource* m_sampleSource;
+	RTLSDRInput* m_sampleSource;
     int m_sampleRate;
     quint64 m_deviceCenterFrequency; //!< Center frequency in device
 	int m_lastEngineState;
diff --git a/plugins/samplesource/rtlsdr/rtlsdrinput.cpp b/plugins/samplesource/rtlsdr/rtlsdrinput.cpp
index 57e43ce9c..0accf0e8d 100644
--- a/plugins/samplesource/rtlsdr/rtlsdrinput.cpp
+++ b/plugins/samplesource/rtlsdr/rtlsdrinput.cpp
@@ -32,7 +32,6 @@
 #include "dsp/filerecord.h"
 
 MESSAGE_CLASS_DEFINITION(RTLSDRInput::MsgConfigureRTLSDR, Message)
-MESSAGE_CLASS_DEFINITION(RTLSDRInput::MsgReportRTLSDR, Message)
 MESSAGE_CLASS_DEFINITION(RTLSDRInput::MsgFileRecord, Message)
 MESSAGE_CLASS_DEFINITION(RTLSDRInput::MsgStartStop, Message)
 
@@ -481,17 +480,6 @@ bool RTLSDRInput::applySettings(const RTLSDRSettings& settings, bool force)
     return true;
 }
 
-void RTLSDRInput::setMessageQueueToGUI(MessageQueue *queue)
-{
-    qDebug("RTLSDRInput::setMessageQueueToGUI: %p", queue);
-    DeviceSampleSource::setMessageQueueToGUI(queue);
-
-    if (queue) {
-        MsgReportRTLSDR *message = MsgReportRTLSDR::create(m_gains);
-        queue->push(message);
-    }
-}
-
 void RTLSDRInput::set_ds_mode(int on)
 {
 	rtlsdr_set_direct_sampling(m_dev, on);
diff --git a/plugins/samplesource/rtlsdr/rtlsdrinput.h b/plugins/samplesource/rtlsdr/rtlsdrinput.h
index 7b6b7c911..54a82d67f 100644
--- a/plugins/samplesource/rtlsdr/rtlsdrinput.h
+++ b/plugins/samplesource/rtlsdr/rtlsdrinput.h
@@ -53,26 +53,6 @@ public:
 		{ }
 	};
 
-    class MsgReportRTLSDR : public Message {
-        MESSAGE_CLASS_DECLARATION
-
-    public:
-        const std::vector<int>& getGains() const { return m_gains; }
-
-        static MsgReportRTLSDR* create(const std::vector<int>& gains)
-        {
-            return new MsgReportRTLSDR(gains);
-        }
-
-    protected:
-        std::vector<int> m_gains;
-
-        MsgReportRTLSDR(const std::vector<int>& gains) :
-            Message(),
-            m_gains(gains)
-        { }
-    };
-
     class MsgFileRecord : public Message {
         MESSAGE_CLASS_DECLARATION
 
@@ -118,12 +98,12 @@ public:
 	virtual bool start();
 	virtual void stop();
 
+    virtual void setMessageQueueToGUI(MessageQueue *queue) { m_guiMessageQueue = queue; }
 	virtual const QString& getDeviceDescription() const;
 	virtual int getSampleRate() const;
 	virtual quint64 getCenterFrequency() const;
 
 	virtual bool handleMessage(const Message& message);
-	virtual void setMessageQueueToGUI(MessageQueue *queue);
 
     virtual int webapiSettingsGet(
                 SWGSDRangel::SWGDeviceSettings& response,
diff --git a/plugins/samplesource/sdrdaemonsource/sdrdaemonsourceinput.cpp b/plugins/samplesource/sdrdaemonsource/sdrdaemonsourceinput.cpp
index 9b4ed86d0..5bbb06b5d 100644
--- a/plugins/samplesource/sdrdaemonsource/sdrdaemonsourceinput.cpp
+++ b/plugins/samplesource/sdrdaemonsource/sdrdaemonsourceinput.cpp
@@ -54,7 +54,8 @@ SDRdaemonSourceInput::SDRdaemonSourceInput(DeviceSourceAPI *deviceAPI) :
     m_autoCorrBuffer(false)
 {
 	m_sampleFifo.setSize(96000 * 4);
-	m_SDRdaemonUDPHandler = new SDRdaemonSourceUDPHandler(&m_sampleFifo, &m_inputMessageQueue, m_deviceAPI);
+	//m_SDRdaemonUDPHandler = new SDRdaemonSourceUDPHandler(&m_sampleFifo, &m_inputMessageQueue, m_deviceAPI);
+	m_SDRdaemonUDPHandler = new SDRdaemonSourceUDPHandler(&m_sampleFifo, m_deviceAPI);
 	m_SDRdaemonUDPHandler->connectTimer(&m_masterTimer);
 
     char recFileNameCStr[30];
@@ -91,6 +92,12 @@ void SDRdaemonSourceInput::stop()
 	getInputMessageQueue()->push(command);
 }
 
+void SDRdaemonSourceInput::setMessageQueueToGUI(MessageQueue *queue)
+{
+    m_guiMessageQueue = queue;
+    m_SDRdaemonUDPHandler->setMessageQueueToGUI(queue);
+}
+
 const QString& SDRdaemonSourceInput::getDeviceDescription() const
 {
 	return m_deviceDescription;
@@ -224,13 +231,6 @@ bool SDRdaemonSourceInput::handleMessage(const Message& message)
 	}
 }
 
-void SDRdaemonSourceInput::setMessageQueueToGUI(MessageQueue *queue)
-{
-    qDebug("SDRdaemonSourceInput::setMessageQueueToGUI: %p", queue);
-    DeviceSampleSource::setMessageQueueToGUI(queue);
-    m_SDRdaemonUDPHandler->setMessageQueueToGUI(queue);
-}
-
 int SDRdaemonSourceInput::webapiRunGet(
         SWGSDRangel::SWGDeviceState& response,
         QString& errorMessage __attribute__((unused)))
diff --git a/plugins/samplesource/sdrdaemonsource/sdrdaemonsourceinput.h b/plugins/samplesource/sdrdaemonsource/sdrdaemonsourceinput.h
index cc5f1f02e..5fdcb87ff 100644
--- a/plugins/samplesource/sdrdaemonsource/sdrdaemonsourceinput.h
+++ b/plugins/samplesource/sdrdaemonsource/sdrdaemonsourceinput.h
@@ -329,6 +329,7 @@ public:
 	virtual bool start();
 	virtual void stop();
 
+    virtual void setMessageQueueToGUI(MessageQueue *queue);
 	virtual const QString& getDeviceDescription() const;
 	virtual int getSampleRate() const;
 	virtual quint64 getCenterFrequency() const;
@@ -337,8 +338,6 @@ public:
 
 	virtual bool handleMessage(const Message& message);
 
-	virtual void setMessageQueueToGUI(MessageQueue *queue);
-
     virtual int webapiRunGet(
             SWGSDRangel::SWGDeviceState& response,
             QString& errorMessage);
diff --git a/plugins/samplesource/sdrdaemonsource/sdrdaemonsourceudphandler.cpp b/plugins/samplesource/sdrdaemonsource/sdrdaemonsourceudphandler.cpp
index 58eae51fc..66bcf3be7 100644
--- a/plugins/samplesource/sdrdaemonsource/sdrdaemonsourceudphandler.cpp
+++ b/plugins/samplesource/sdrdaemonsource/sdrdaemonsourceudphandler.cpp
@@ -26,7 +26,7 @@
 #include "sdrdaemonsourceinput.h"
 #include "sdrdaemonsourceudphandler.h"
 
-SDRdaemonSourceUDPHandler::SDRdaemonSourceUDPHandler(SampleSinkFifo *sampleFifo, MessageQueue *outputMessageQueueToGUI, DeviceSourceAPI *devieAPI) :
+SDRdaemonSourceUDPHandler::SDRdaemonSourceUDPHandler(SampleSinkFifo *sampleFifo, DeviceSourceAPI *devieAPI) :
     m_deviceAPI(devieAPI),
 	m_sdrDaemonBuffer(m_rateDivider),
 	m_dataSocket(0),
@@ -41,7 +41,7 @@ SDRdaemonSourceUDPHandler::SDRdaemonSourceUDPHandler(SampleSinkFifo *sampleFifo,
 	m_centerFrequency(0),
 	m_tv_sec(0),
 	m_tv_usec(0),
-	m_outputMessageQueueToGUI(outputMessageQueueToGUI),
+	m_outputMessageQueueToGUI(0),
 	m_tickCount(0),
 	m_samplesCount(0),
 	m_timer(0),
@@ -244,22 +244,25 @@ void SDRdaemonSourceUDPHandler::tick()
 			framesDecodingStatus = 2;
 		}
 
-		SDRdaemonSourceInput::MsgReportSDRdaemonSourceStreamTiming *report = SDRdaemonSourceInput::MsgReportSDRdaemonSourceStreamTiming::create(
-			m_tv_sec,
-			m_tv_usec,
-			m_sdrDaemonBuffer.getBufferLengthInSecs(),
-            m_sdrDaemonBuffer.getBufferGauge(),
-            framesDecodingStatus,
-            minNbBlocks == nbOriginalBlocks + nbFECblocks,
-            minNbBlocks,
-            minNbOriginalBlocks,
-            m_sdrDaemonBuffer.getMaxNbRecovery(),
-            m_sdrDaemonBuffer.getAvgNbBlocks(),
-            m_sdrDaemonBuffer.getAvgOriginalBlocks(),
-            m_sdrDaemonBuffer.getAvgNbRecovery(),
-            nbOriginalBlocks,
-            nbFECblocks);
+		if (m_outputMessageQueueToGUI)
+		{
+	        SDRdaemonSourceInput::MsgReportSDRdaemonSourceStreamTiming *report = SDRdaemonSourceInput::MsgReportSDRdaemonSourceStreamTiming::create(
+	            m_tv_sec,
+	            m_tv_usec,
+	            m_sdrDaemonBuffer.getBufferLengthInSecs(),
+	            m_sdrDaemonBuffer.getBufferGauge(),
+	            framesDecodingStatus,
+	            minNbBlocks == nbOriginalBlocks + nbFECblocks,
+	            minNbBlocks,
+	            minNbOriginalBlocks,
+	            m_sdrDaemonBuffer.getMaxNbRecovery(),
+	            m_sdrDaemonBuffer.getAvgNbBlocks(),
+	            m_sdrDaemonBuffer.getAvgOriginalBlocks(),
+	            m_sdrDaemonBuffer.getAvgNbRecovery(),
+	            nbOriginalBlocks,
+	            nbFECblocks);
 
-            m_outputMessageQueueToGUI->push(report);
+	            m_outputMessageQueueToGUI->push(report);
+		}
 	}
 }
diff --git a/plugins/samplesource/sdrdaemonsource/sdrdaemonsourceudphandler.h b/plugins/samplesource/sdrdaemonsource/sdrdaemonsourceudphandler.h
index 47cf5689f..2ef6bd05e 100644
--- a/plugins/samplesource/sdrdaemonsource/sdrdaemonsourceudphandler.h
+++ b/plugins/samplesource/sdrdaemonsource/sdrdaemonsourceudphandler.h
@@ -36,7 +36,7 @@ class SDRdaemonSourceUDPHandler : public QObject
 {
 	Q_OBJECT
 public:
-	SDRdaemonSourceUDPHandler(SampleSinkFifo* sampleFifo, MessageQueue *outputMessageQueueToGUI, DeviceSourceAPI *deviceAPI);
+	SDRdaemonSourceUDPHandler(SampleSinkFifo* sampleFifo, DeviceSourceAPI *deviceAPI);
 	~SDRdaemonSourceUDPHandler();
 	void setMessageQueueToGUI(MessageQueue *queue) { m_outputMessageQueueToGUI = queue; }
 	void connectTimer(const QTimer* timer);
diff --git a/plugins/samplesource/sdrplay/sdrplayinput.h b/plugins/samplesource/sdrplay/sdrplayinput.h
index b82e057ac..f1b90e98b 100644
--- a/plugins/samplesource/sdrplay/sdrplayinput.h
+++ b/plugins/samplesource/sdrplay/sdrplayinput.h
@@ -135,6 +135,7 @@ public:
     virtual bool start();
     virtual void stop();
 
+    virtual void setMessageQueueToGUI(MessageQueue *queue) { m_guiMessageQueue = queue; }
     virtual const QString& getDeviceDescription() const;
     virtual int getSampleRate() const;
     virtual quint64 getCenterFrequency() const;
diff --git a/sdrbase/dsp/devicesamplesink.h b/sdrbase/dsp/devicesamplesink.h
index 5c425c7a6..a76d8d18e 100644
--- a/sdrbase/dsp/devicesamplesink.h
+++ b/sdrbase/dsp/devicesamplesink.h
@@ -69,7 +69,7 @@ public:
     { errorMessage = "Not implemented"; return 501; }
 
 	MessageQueue *getInputMessageQueue() { return &m_inputMessageQueue; }
-    void setMessageQueueToGUI(MessageQueue *queue) { m_guiMessageQueue = queue; }
+    virtual void setMessageQueueToGUI(MessageQueue *queue) = 0; // pure virtual so that child classes must have to deal with this
     MessageQueue *getMessageQueueToGUI() { return m_guiMessageQueue; }
 	SampleSourceFifo* getSampleFifo() { return &m_sampleSourceFifo; }
 
diff --git a/sdrbase/dsp/devicesamplesource.h b/sdrbase/dsp/devicesamplesource.h
index 479c2b5b8..88971024b 100644
--- a/sdrbase/dsp/devicesamplesource.h
+++ b/sdrbase/dsp/devicesamplesource.h
@@ -69,7 +69,7 @@ public:
     { errorMessage = "Not implemented"; return 501; }
 
 	MessageQueue *getInputMessageQueue() { return &m_inputMessageQueue; }
-	virtual void setMessageQueueToGUI(MessageQueue *queue) { m_guiMessageQueue = queue; }
+	virtual void setMessageQueueToGUI(MessageQueue *queue) = 0; // pure virtual so that child classes must have to deal with this
 	MessageQueue *getMessageQueueToGUI() { return m_guiMessageQueue; }
     SampleSinkFifo* getSampleFifo() { return &m_sampleFifo; }