You have a HiFonics 440 is a 4 channel amp. How do you plan to run your sub? You'll need a seperate mono amp.

Look for a headunit with 3 sets of preouts, front, rear, and non-fading sub.

This is where you need to decide how much you really want to spend.

I would looked for the following things:

Removable face

4-6v output

100Db + of signal/noise on CD playback

I wanted to be able to play DVD-A also, I want to play SACD in the car too, but haven't found a HU to do it yet.

I really like the better sony ES line, some of the better Eclipse units, and some of the Alpines.

Its hard to pick a unit for you without an idea of budget.

John C.