I’m doing a backing track mix where the click is in the left channel and the backing track is in the right channel. I always mix backing tracks so the loudest peaks are at -2db in the final bounce.
I have a stereo group channel feeding a mono output channel and I’m seeing the output levels hit -0.3 db even though I have a limiter set to -2 db in the insert chain, the signal going into limiter never hits the -2db threshold. Feeding the stereo channel to a mono channel looks like it changes the stereo channel to mono. Should I be dropping the output of the stereo group by 3 db to compensate?
Just figured it out, the answer is yes. If you send a stereo bus to a mono output, set the fader on the stereo group to -3db and everything lines up nicely. Approximately 3 people might find this useful. 
Did I mention? VCA channels rock!
Could you say a little more about how you’re using these backing tracks?
I’ve been thinking of using some backing tracks for a band or two.
I think you’re right about the general levels, but gain staging and good qualaity output signal to the monitors is, of course, essential. one board we have has a USB input, but I’m not sure if it for control functions only, or if the board can take a stereo mix and send that to the speakers – that would be idea.
Good luck with your projects.