Well, I'm using an Alpine MRP-F356, which is a 5 channel amp, with 75w x 4, and 180w sub. The only reason I'm using this amp, is because it was the biggest 5 channel amp I could find that fit under the seat. I didn't want to take up more trunk space than I had to, so that was one of my primary requisites. Not that Alpine makes a bad amp, to be honest I've been pretty happy with mine. But, If I had more room (& money), I would have gone with separates. Something like Nakamichi for the mids and tweets, and something fairly basic, but large for the sub. I've been really happy with that setup before. From my experience, it's best to go top of the line for the mids and tweets, because that's the area where THD and S/N ratio are the most obvious. For a sub, you really just want something that has lots of power, and won't overheat or cut out under a load. I had a nice bandpass box with a pair of 10s in my last ride, and I ran that with a Rockford Fosgate punch 150, and it sounded great. Never cut out, got distorted, or overheated. So, that would probably be my recommendation. Not the best amp in the world, but pretty good for a sub, and won't break the bank either.