I have a Kenwood KDC522 deck pushing factory 6" Bose door speakers (with their own built in amps). I added my 10" JL sub (hooked up to rear preamp outs).
I'm concerned about pushing the door speakers with too much bass. In fact I've had to turn the bass down. Deck has xover, but doesn't have separate sub out so if I use xover it will cut lo-freq's to sub - no good.
Deck also has another feature whereby you can choose speaker sizes 4-5"/6-6x9/OEM or just leave it off. I'm guessing this is sort of a "preset" xover. The documentation is weak so I'm not sure. But afraid again it might block lo-freqs to the rear pre-amp out.
Considering bass blockers. I've read somewhere that you want to put them as close to speakers as possible. Is there a problem putting them right next to speaker which also happens to be where the Bose amp is located? Would this be OK? Or is proximity to amp a problem?
trash the factory bose speakers, get a nice set of component speakers for the front, something nice for the back dec or door, then get a 4 channel amp for the door and rear dash speakers. make sure the amp has EQ controls on it and you are all set.
costs more then bass blockers, but you will be SO MUCH happier with the results.