Index: /trunk/src/VBox/Devices/Audio/AudioMixBuffer.cpp
===================================================================
--- /trunk/src/VBox/Devices/Audio/AudioMixBuffer.cpp	(revision 61343)
+++ /trunk/src/VBox/Devices/Audio/AudioMixBuffer.cpp	(revision 61344)
@@ -42,6 +42,4 @@
 #include <iprt/mem.h>
 #include <iprt/string.h> /* For RT_BZERO. */
-
-#define VBOX_AUDIO_TESTCASE
 
 #ifdef VBOX_AUDIO_TESTCASE
@@ -1626,5 +1624,8 @@
 
     if (offSamples + cToWrite > pMixBuf->cSamples)
+    {
+        RT_BREAKPOINT();
         rc = VINF_BUFFER_OVERFLOW;
+    }
 
     cToWrite = RT_MIN(cToWrite, pMixBuf->cSamples - offSamples);