I broke down and bought another amplifier for the car
The lack of clean sound coming from the AVN6600's bulit in amplifier started getting to me and I started looking around for cheap used amplifiers, just for kicks. Then one day, Vijay told me (paraphrased), "When you have kids, you won't have time or money for this kind of stuff anymore, take advantage of it now. Plus, you have pretty much everything else in the car in terms of car audio, might as well add this one final little piece." Ok, that convinced me. I ended up getting an older 4 channel Alpine MRP-F200. It's one of Alpine's weaker amps, but it does have a little more kick than the even weaker MRH-F254 I used to have in the Civic. I dunno if $70 was worth it, but I don't think it was a terrible deal. It should do the trick! It's coming in the mail right now, hopefully I'll REALLY have the car audio squared away by next weekend. Can't wait to take apart my backseat again to mount the amplifier! (that was somewhat sarcastic)
As a side note, I think there is a loose connection in my driver side speaker. I'm gonna have to remove the door panel and get in to see what's going on. I'll probably have to re-wire it a bit and find a better mounting spot for the crossover inside. I believe I just taped it to the door panel with tape! Bad me, I should do a better job this time around.
As another side note, I put up some pictures of the AVN6600 on the pictures page of our website. They're not the greatest pictures, but they'll do.