tomfowler

Hi all, just a quick question. I'm looking at getting a new headunit for my IS. I've been reading threads and it looks like any headunit I get I will have to bypass the amp, will this make the sound quality bad? - If not, i'm guessing I would have to fit the headunit myself as I doubt somewhere like Halfords would know about bypassing it? or would they? Also, just to confirm, a double din unit will fit in it, correct?