Need some advice on amps...

[bunghole]

I posted this over at CustomTacos as well, but since I'm insanely impatient, I figured I'd pester the stereo experts over here as well. Any help y'all could give me would be appreciated.

Here's what I've done so far ('06 Tacoma Double Cab):

AVIC D3 HU

Here's whats a comin'

Pioneer Premier TS-C720PRS
TacoTunes speaker mounts
Scosche Sub Box (I know the reviews aren't great, but I really want to leave the interior as stock as possible)
Sound deadening in the doors at least.
I'll power the stock rears with the HU and fade it out (seems to be the consensus around here)

Here's where I need advice:

What amp / amps should I go with? Should I get a 4 channel and bridge for the sub or should I get a dedicated sub amp? I would like to be very stealth and mount the subs out of the way (and keep the storage areas behind / under the rear seats as much as possible. I would like to keep the amp budget under $500 total, but if sound quality get significantly better for more, I'm willing to stretch.

I'm mainly interested in sound quality at all volume levels and don't need eardrum shattering volume.

This will be my first ever DIY install, so any tips would help as well.

Thanks in advance to all of you experts out there.

[xet]

you will most likely need two seperate amps, one for the speakers, one for the subs. The sub most likely will require more power than the speakers so a 4 channel amp usually wouldnt work. Also you are going to need to set the gains on the amps as well as the lpf, hpf, etc on different levels for the speakers and sub