What the Guys have said above, is exactly right.

As a note to you, why would you purchase the Empeg and just magically think it was going to work in your car. Many radio manufactures make special units just for different car makes. Other companys deal with parts just to make after market radios work in just about any car. As for no internal amp, you just said its too big to fit your car now, and internal amp would make the unit bigger yet, or you could only fit one HD in it. Most high end car radios do not have internal amps so that the sound is prority.
Empeg has all specs listed on thier web site, inputs, outputs and size.

It seems like you just didn't read enough before the purchase. Don't make Empeg sound like they didn't inform you well enough.

Once you get that thing working, you will see its worth the trouble. Its an awesome product. I hope you have it working soon.

I love mine, it sounds great and everyone who sees it, is amazed!