Hi there~
The channel 5 is playback channel. if you plug the mic array v2.0 to PC and then you select mic array v2.0 as audio output device, you can see the data on channel 5. thanks.
Channel 0: processed audio for ASR
Channel 1: mic1 raw data
Channel 2: mic2 raw data
Channel 3: mic3 raw data
Channel 4: mic4 raw data
Channel 5: merged playback