Pioneer DEH-P4600 Car CD / MP3 Player

I got this head unit in a deal with some used speakers.  I already had a Pioneer head unit, but figured I'd try it out since I had it and it was a bit newer than my HU (DEH-P3500) and it had MP3 CD playback.  It didn't fit the color scheme of the rest of my car.  No other light on my car is bright blue...  I wasn't given a wiring harness, but it hooked right up to my old one.  Playing with it I set the time and stuff and it was the same idea, but later realized during night time there was no Dimmer setting that I noticed.  I sat there playing with the audio settings and EQ forever trying to get a decent sound out of my aftermarket Alpine rears and Phoenix Gold fronts.  It took me awhile, but I got to a sound that was ok until I switched back to my old HU.  Bass is really screwy.  Made my Alpines sound stiff or something.  Made all the speakers sound tinny.  Phoenix Golds had no bass whatsoever.  If I set for more bass it would just get distorted.  I finally switched back to my old HU yesterday.  Sounded awesome off the bat.  Changed settings and it only got better.  My old HU made the stock speakers in my car sound really good, they just distorted at higher voumes.  I'm going to just sell the DEH-P4600 hoping someone else will have more luck with it than I did.  Maybe it didn't like my speakers...I don't know.  I never got a chance to check out MP3 CD playback because I was so annoyed by the sound quality.