Index: /trunk/src/VBox/Devices/Audio/DrvHostCoreAudio.cpp
===================================================================
--- /trunk/src/VBox/Devices/Audio/DrvHostCoreAudio.cpp	(revision 73679)
+++ /trunk/src/VBox/Devices/Audio/DrvHostCoreAudio.cpp	(revision 73680)
@@ -2449,22 +2449,24 @@
     PCOREAUDIOSTREAM pCAStream = (PCOREAUDIOSTREAM)pStream;
 
-    if (ASMAtomicReadU32(&pCAStream->enmStatus) != COREAUDIOSTATUS_INIT)
-        return 0;
-
-    AssertPtr(pCAStream->pCfg);
-    AssertPtr(pCAStream->pCircBuf);
-
-    switch (pCAStream->pCfg->enmDir)
-    {
-        case PDMAUDIODIR_OUT:
-            return (uint32_t)RTCircBufFree(pCAStream->pCircBuf);
-
-        case PDMAUDIODIR_IN:
-        default:
-            AssertFailed();
-            break;
-    }
-
-    return 0;
+    uint32_t cbWritable = 0;
+
+    if (ASMAtomicReadU32(&pCAStream->enmStatus) == COREAUDIOSTATUS_INIT)
+    {
+        AssertPtr(pCAStream->pCfg);
+        AssertPtr(pCAStream->pCircBuf);
+
+        switch (pCAStream->pCfg->enmDir)
+        {
+            case PDMAUDIODIR_OUT:
+                cbWritable = (uint32_t)RTCircBufFree(pCAStream->pCircBuf);
+                break;
+
+            default:
+                break;
+        }
+    }
+
+    LogFlowFunc(("cbWritable=%RU32\n", cbWritable));
+    return cbWritable;
 }