I currently have the JVC hooked up to a 12" JL 12W3V3 (sealed) via a JL 250w monoblock and polk momo 6500's via a JL 300/2 amp. (Front speakers only)

I already know the the Xonar D1 will produce better sound (it's a computer, DUH) than the JVC, but will I be able to notice it? I have mat and foam in the car, still need to add a bit in the doors when the weather gets warmer and fix the few rattles that are left through the car.

I have a small Mazda MX3 which is why I decided to ditch the rear fill.

Thoughts/help are appreciated!

**Also, I have been reading through posts by WuNgUn, and he seems to have a pretty serious setup using the Xonar to actively control his crossovers. I don't know much about this. (I have the passive crossovers from the polks) Wouldn't I need to bi-amp (or get a 4 channel) the front speakers if I were to do this since I'm only running a 2 channel amp? One for tweets L/R and the other for Mids L/R?

I'd like the best SQ I can get for the money, without spending ridiculous amounts or building my own amps. I like to think my speakers/amps are of decent quality. (what do you think?)