Index: /trunk/src/VBox/Devices/Makefile.kmk
===================================================================
--- /trunk/src/VBox/Devices/Makefile.kmk	(revision 68232)
+++ /trunk/src/VBox/Devices/Makefile.kmk	(revision 68233)
@@ -567,5 +567,5 @@
 
  # Enable backend callback support.
- #VBoxDD_DEFS  += VBOX_WITH_AUDIO_CALLBACKS
+ VBoxDD_DEFS  += VBOX_WITH_AUDIO_CALLBACKS
 
  # Disable one-time audio stream initialization at device creation (VM startup) instead