Index: /trunk/src/VBox/Devices/Audio/DrvHostNullAudio.cpp
===================================================================
--- /trunk/src/VBox/Devices/Audio/DrvHostNullAudio.cpp	(revision 73571)
+++ /trunk/src/VBox/Devices/Audio/DrvHostNullAudio.cpp	(revision 73572)
@@ -162,6 +162,9 @@
     RT_NOREF(pInterface, pStream);
 
+    PNULLAUDIOSTREAM pStreamNull = (PNULLAUDIOSTREAM)pStream;
+
     /* Return silence. */
-    RT_BZERO(pvBuf, cxBuf);
+    Assert(pStreamNull->pCfg);
+    DrvAudioHlpClearBuf(&pStreamNull->pCfg->Props, pvBuf, cxBuf, PDMAUDIOPCMPROPS_B2F(&pStreamNull->pCfg->Props, cxBuf));
 
     if (pcxRead)