You can replace your factory alpine amp. Kenwood make a plug & play alternative that will completely replace the factory amp.
Additionally, you can pull/disconnect channels from the factory harness and redirect them. I currently have a AC D6.1200 running my front corners, my front doors, and my rear doors. I have a kenwood running a JL 10TW stealthbox, and have the factory unit pushing the center channel and the headliners. Absolutely no issues. Just saying.
I appreciate the info on that! Not going to do any more replacing for now - but I did swap the JBL I mentioned in my previous post (the one I cut the mid-range out of) with the other JBL that I cut the tweeter out of. The system sounds great.
Good bass, clear mids and highs. There's a little bit of "hiss" when people are using words that end in "s" but that's about it. I did have to turn down the treble to get rid of the rings and brightness, no matter what.
I am considering ordering a Hertz 87.3 for the center channel, because I suspect the JBL (2.5 ohm, tweeter cut out) I'm using there now, is just too "loud" compared to the other speakers in my car, which are all 4 ohm - excluding the sub, but the Hertz just doesn't really have a lot of power handling capability (60 Watts peak)... The Audiofrog GS25's would be good as they can handle 150 watts peak, but, the price is steep on those, and I've frankly thrown more money at this now than I originally wanted to.
If anyone has any recommendations on what to do about my center channel, I'm all ears!
Current Setup:
Infinity Reference REF-375TX - 4 ohm tweeters - dash corners and headliner
JBL Club 322f - 2.5 ohm - tweeter cut out - center channel
Pioneer TS-G690 - front and rear doors - 4 ohm full range
Pionner TS-SW2002D2 subwoofer - dual voice coil wired at 2 ohms.