josq wrote:Reaper will receive these audio outputs on separate tracks (as I just described above), which will enable you to send them to separate hardware outputs (=speakers/speaker pairs).
Yes, no problem getting six discrete channels (configured as 3 stereo pairs) to appear on six separate inputs in Reaper, nor was there a problem routing them to six separate outputs. The problem was that each output had a mix of all the channels, not just the one assigned to it in the output matrix. At the time, the tutorial was no help in resolving the issue as the Reaper interface had changed, but according to the Reaper documentation, what I had done should have worked.
Anyway, this was a couple of years ago and I've moved on, but thanks for taking the time to help. Perhaps I'll find reason to try it again someday.