Index: /trunk/src/VBox/Devices/Audio/DrvHostDSound.cpp
===================================================================
--- /trunk/src/VBox/Devices/Audio/DrvHostDSound.cpp	(revision 73691)
+++ /trunk/src/VBox/Devices/Audio/DrvHostDSound.cpp	(revision 73692)
@@ -765,7 +765,11 @@
         pThis->pDSStrmOut = pStreamDS;
 
-        pCfgAcq->Backend.cfBufferSize = PDMAUDIOSTREAMCFG_B2F(pCfgAcq, pStreamDS->cbBufSize);
-        pCfgAcq->Backend.cfPeriod     = pCfgAcq->Backend.cfBufferSize / 2;
-        pCfgAcq->Backend.cfPreBuf     = pCfgAcq->Backend.cfBufferSize;
+        const uint32_t cfBufSize = PDMAUDIOSTREAMCFG_B2F(pCfgAcq, pStreamDS->cbBufSize);
+        if (cfBufSize != pCfgAcq->Backend.cfBufferSize)
+        {
+            pCfgAcq->Backend.cfBufferSize = cfBufSize;
+            pCfgAcq->Backend.cfPeriod     = cfBufSize / 4;
+            pCfgAcq->Backend.cfPreBuf     = pCfgAcq->Backend.cfPeriod * 2;
+        }
 
     } while (0);