In 99% of occurrences, yes, Audio and MIDI can be intertwined, but in this particular project, I was using MIDI CC and PC messages to change preset and paramete

In 99% of occurrences, yes, Audio and MIDI can be intertwined, but in this particular project, I was using MIDI CC and PC messages to change preset and parameter settings on a rack mounted effects processor. Oh, and we needed to use SYSEX a LOT in order to intercept clock timing messages, as well as complex data like preset names and multi parameter effect settings (EQ etc.). None of the messages sent/received affected music notes at all - it was all setting configuration only.