I'm currently going through the process of installing a system in my 1995 VR6 Golf.
I'm pretty sure the sound quality, and the ability to tweak it should be fairly straight forward if you get hold of a 5.1 sound card. That way, you'll be able to amp the line outs just as you would a normal car stereo. That's what I'm doing anyway!
I've got an old laptop that just has a stereo output, so need to get myself an external USB sound card to up the channels to 5.1. The plan is then to have an amp for the rear, an amp for the fronts, and an amp for the sub. Might even get a teeny tiny amp for a front central speaker too! LoL!
Anyway, good luck, and keep us "Posted"