Hi manolito, thanks for the double check with VirtualDub2 and MPC-HC.
Another oddity with MPC-HC is that anytime I feed it with a simple AVISource() script, it chokes (no render). Since AVISource is the first choice in A2DSource, that could be another reason of preview failure with MPC-HC.
The AVSMeter workaround to grab audio channels works well. E.g. some dolby atmos tracks are read by MediaInfo as "15 objects / 6 channels". Very, very misleading. AVSMeter way or improved MediaInfo string parsing? Will do some testing. If you have any other exotic audio tracks, please advise.
Bye