Mixing tracks using two instances of OpenMPT

[Saga Musix]

I did not find any licensing information, but the fact that you have to contact them personally to get more information as a developer already sounds like it will be incompatible with open-source software. Besides, if I had to implement an external protocol, I'd rather implement something like JACK that is free and open-source.

[Exhale]

A long long time ago I experimented with this... I will check up on my old files and get back to you but the things I learned :

I was making / mixing at the same time, messing around with the highpass / lowpass filters, volume etc while going along - but of course much automation is possible with variation on when loops happen etc, modplug is great for that.
Playing with filters live was also awesome, so yeah I really recommend this. Obviously you can plug a mic in and play that through your speakers too, but I admit I didnt mess with that at the time, as I was really just experimenting.

The files tended to be looped and somewhat repetative