If I continue with the tutorials I may be able to answer more questions.

Like I said, I am just fumbling with this thing right now. As for modifying the stem filter settings, I don't know. You can definitely 'goose the rears' of a 5.1 file, but you could do that with any wav editor. It's always intimidated me and because they have added more AI and more tools, a rookie like me can do more than I could before. Me? I am a total clueless newbie at this program. I doubt that you can pull out a soloist from a choir recording without serious artifacts, but I would guess you'd have to be really familiar with the software to try. There is a tutorial on this where a guy dissects the percussion stem into different bits. There are two extraction modes, you can extract the stems, but you can also extract 'components'. I don't have a lot of time for PC today (family stuff), but I did mess around a bit with it this morning. The first thing I noticed is that it opens a 5.1 file, for real! It also supported playback in 5.1 on my PC, so that was very cool to see and hear. It's fairly sophisticated and I know I will never be an expert or even good at it, but I like to play around with this stuff. I had used the program in the past to tweak up some audio on some conversions I'd done so I knew the deal. This week I got an offer to upgrade my copy of the software to Version 7 for $79, so I checked it out and saw that it too now had a stem separation feature, so I decided to go for it. All along it's been a powerful spectral editor but it has a very steep learning curve and unless you do this kind of thing for real, like a job, most hobby guys don't have the time or patience to really get into it and learn it. SpectraLayers has been around for many years, first as a Sony product, then a MAGIX program, and now it's owned by Steinberg. There are also many new comers like Penteo (which isn't really that new, it's founder, John Wheeler was/is a member here from way back when), spleeter, Acoustica 7, and the newest version of Acid Pro are other programs that can extract stems. The SurroundByUs guys started it all and their SPEC program has been a trail blazer in the field, and is still today one of the top choices for folks who like to upmix stuff to quad, 5.1 and beyond. There's been a lot of talk around here about stems and upmixing lately, and that's all good.

Spectralayers pro 4 tutorial