I have a Helix with Variax (James Tyler) guitar and I have a Mac mini with it currently attached. A Tascam US 2x2. I regularly play music or watch Youtubes with tests etc. on the Mac, but sometimes I also want to play guitar, either through my headphones or sometimes through my presonus-eris-e5-xt-active-studio monitors. Now I always have the problem that I always have to start a Tascam app because the guitar is of course mono so if I just switch from my mini to guitar, I have to switch from stereo to mono, otherwise an irritant noise. Any idea for an external music card or mixer where I can connect all this directly and (easily) jump from one to the other? p.s. at the moment I am not running Big Sur (yet) because this will probably cause problems with my Helix.