Thanks OOPer :) Yes, this is certainly a strange way to try and learn Swift. I am an experienced C programmer. So I'll also take a short look at writing the whole thing in C. Not sure which would be more fun/frustrating. Thanks for the code ideas. I see some potential there.

I think this might be an operating system problem related to resource allocation, maybe alignment. I see the following consistently (You may think this is an Ableton problem, but hear me out). Everything is fine. I search "Relaxing Music" on Youtube and play this "24/7" video. Thick pads. Sweet. Let it play as I continue. (seriously, pick something relaxing) I start a new Live Set (empty project) I go into Live's audio preferences and set the Buffer Size in Latency settings in Ableton Live to 32 samples (the default is 512). I hear some crackling in my Youtube sound right when the change is made, not much, and it stops after a bit, I think. I set the buffer size back to 512 and it goes away completely. I open a Live Set that has 8 tracks of Spitfire Studio Strings. I set the buffer size back to 32. (Note, I am still not playing anything in Live) I hear lots of crackling that continues. (Alternate adventure: at this point, I could exit Live and it would stop the crackling. Open the project again, back to crackling) Change the buffer size back to 512. 10. Zero crackling. (continue playing relaxing music for a while)