I actually have two amps right now. The first one is a Kicker 750.1 and I'm pushing the 2 MTX twelves with it. I hooked it up with the Trunk-LOC on the subwoofer output of the factory amp. It's an 06 amplifier so it came out before they switched those to balanced inputs.
The new amp I recently picked up is an Oz Audio 50.4. I was hoping that it would have balanced inputs since Oz was known for making pretty high-end stuff. To my dismay when I pulled the cover off of the amp, I saw the RCA grounds connected together. I'd still like to use the amp because I got a fantastic deal on it.
I've been searching all over Bimmerpost for a month trying to find some clarification on what you can do to get around the issue of balanced versus unbalanced inputs. The only thing I have found are serveral people talking about how clean the balanced signal is and how you can plug it into a Zapco DC amp with a couple of resisters. I think my wife would shoot me if I bought an $800 amplifier!! :-)