Electric guitar...

I know you want info on the Tascam JPar, but the app I use is Anytune Pro+. It’s been very handy for me, but I’ll also route my Katana amp through my computer and do things that way. Not sure if that will help you?

The Anytune app will take songs you have in your phone and you will be able to slow it down to whatever you want and adjust for different keys and pitches.