Blankman I'd pass on replacing what you already have w/ another of same. Why? B/c you'll again face the same issues sooner rather than later. Furthermore, someone didn't remove theirs b/c they loved it so much and wanted to save it for posterity - LOL.
Of hand I do not recall specifically who makes an optic compatible unit but check the regular suspects lik Pioneer, JVC and Apline. That said, depening on the unit itself, you may be able to bypass the existing amp all together and wire the drivers directly to the h/u.
I suspect if you truly look at all the overpriced add on options you would like to have (Dension, Bluetooth, Nav), you'll quickly see how much better a decision it is to just scrap the exiting and go aftermarket. It's a tough pill to swallow up front but in the end it makes more sense.
Good luck and search here and on
6SpeedOnline for more info as many others have preceded you on this journey.