diff --git a/src/blackcore/afv/audio/input.cpp b/src/blackcore/afv/audio/input.cpp
index 4433deef2..be8744a36 100644
--- a/src/blackcore/afv/audio/input.cpp
+++ b/src/blackcore/afv/audio/input.cpp
@@ -90,6 +90,7 @@ namespace BlackCore
             {
                 if (m_started) { return; }
 
+                BLACK_VERIFY_X(inputDevice.isValid() && inputDevice.isInputDevice(), Q_FUNC_INFO, "Wrong input device");
                 m_device = inputDevice;
 
                 QAudioFormat inputFormat;
diff --git a/src/blackcore/afv/audio/output.cpp b/src/blackcore/afv/audio/output.cpp
index 86dc06fe2..143ebed59 100644
--- a/src/blackcore/afv/audio/output.cpp
+++ b/src/blackcore/afv/audio/output.cpp
@@ -9,8 +9,9 @@
 //! \file
 
 #include "output.h"
-#include "blackmisc/logmessage.h"
 #include "blacksound/audioutilities.h"
+#include "blackmisc/logmessage.h"
+#include "blackmisc/verify.h"
 
 #include <QDebug>
 #include <QStringBuilder>
@@ -90,6 +91,9 @@ namespace BlackCore
             {
                 if (m_started) { return; }
 
+                BLACK_VERIFY_X(outputDevice.isValid() && outputDevice.isOutputDevice(), Q_FUNC_INFO, "Wrong output device");
+
+                if (m_audioOutputBuffer) { m_audioOutputBuffer->deleteLater(); }
                 m_audioOutputBuffer = new CAudioOutputBuffer(sampleProvider, this);
                 connect(m_audioOutputBuffer, &CAudioOutputBuffer::outputVolumeStream, this, &COutput::outputVolumeStream);
 
diff --git a/src/blackcore/afv/clients/afvclient.cpp b/src/blackcore/afv/clients/afvclient.cpp
index 8612da25a..04a822e3c 100644
--- a/src/blackcore/afv/clients/afvclient.cpp
+++ b/src/blackcore/afv/clients/afvclient.cpp
@@ -14,6 +14,7 @@
 #include "blacksound/audioutilities.h"
 #include "blackmisc/audio/audiodeviceinfolist.h"
 #include "blackmisc/threadutils.h"
+#include "blackmisc/verify.h"
 
 #ifdef Q_OS_WIN
 #include "comdef.h"
@@ -243,6 +244,9 @@ namespace BlackCore
                     return;
                 }
 
+                BLACK_VERIFY_X(inputDevice.isValid()  && inputDevice.isInputDevice(), Q_FUNC_INFO, "Wrong input device");
+                BLACK_VERIFY_X(outputDevice.isValid() && outputDevice.isOutputDevice(), Q_FUNC_INFO, "Wrong output device");
+
                 if (m_isStarted)
                 {
                     if (this->usesSameDevices(inputDevice, outputDevice))
@@ -829,8 +833,11 @@ namespace BlackCore
             void CAfvClient::onSettingsChanged()
             {
                 const CSettings audioSettings = m_audioSettings.get();
-                this->setNormalizedInputVolume(audioSettings.getInVolume());
-                this->setNormalizedOutputVolume(audioSettings.getOutVolume());
+                const int iv = audioSettings.getInVolume();
+                const int ov = audioSettings.getOutVolume();
+
+                this->setNormalizedInputVolume(iv);
+                this->setNormalizedOutputVolume(ov);
                 this->setBypassEffects(!audioSettings.isAudioEffectsEnabled());
             }