"I'm not sure if the Line 6 works in that you can load MP3's onto an SD card, and then play them back through the amp? (Haghj?)."
The Jam has a mp3 in jack so you can play the mp3 through the amp, you can also record off the mp3 device to the amp, you can jam with mp3 player and record yourself. You can record a little over 90 tracks. The draw back is, is its like an old cassette recorder, once you hit record it start recording, so it can be hard to time each of the tracks you record and no onboard editing software. The up shot, you can save it off to a SD card, pop it in the computer and edit away.
If a buddy drops by with another instrument he can plug in and both play with separate setting for both instruments and record it all if you choose. It also has a separate mic jack.
Its really not a mp3 jack, it will record from what ever you plug in the jack, once recorded it can be slowed down to just 25% of its original speed or the key changed. So you record something you want to learn, figure out the bass lines or leads in the key it was recorded in, then change the key of the song and relearn the lines or leads much quicker in another key. Maybe at 40 % of the original speed ha ha.
So did I say I'm was still just scratching the surface of what this amp can do to help a new player, or like myself, long time player looking for something to jam with and continue to enjoy learning.