When using BASS and ASIO number of channels is set to number of available output Channels. This is wrong.

Take for instance an ATI HDIM device that reports 8 channels. This will use all eight channels, but will send silence in 6 of them.

Doing this will prevent usage (My Denon) of any Matrix effect that translates a 2 channel input to 5, since it thinks all channels are already in use. The fix is simple, just remove

_asioNumberChannels = info.outputs;