I have set a zone that plays multichannel music file in its original format, i.e. it does not have any MC's DSP applied except that it has HDMI bitstreaming. The Audio Device selected is WASAPI. My Win 10 PC is connected to Yamaha RX-A3070 AVR via HDMI. The Yamaha AVR uses "Straight" sound mode, thereby bypassing any built-in DSP.
6 channel music (DTS, Dolby Digital, MPL etc) plays fine, but I notice that when playing 4 or 5 channel music, the AVR front panel shows only 3 channel, FL+FR+SW and there is no sound coming out from SR+SL+SBR+SBL. However, when I set the zone's Audio Device in MC24 to Directsound, the AVR front panel displays all channels as active and sound does come out from all speakers. Besides, the volume under Directsound seems to be noticeably higher that that under WASAPI.
I always thought WASAPI should perform better than Directsound. Has the latest Windows update enhanced Directsound somehow?
I am puzzled! I truly appreciate the forum's comments and advice. Many thanks.