Underpowered, get a small amp for interior speakers, you can find one pretty cheap at a pawn shop or something like that.
Also note that if there are tweeters present int the 6x9's, then you shouldn't be running any bass to them, most 6x9's are used for loudness, not bass, leave that up to the 12's.
Using the amp I mentioned above, you can set the frequency for them without sacrificing bass control to the subs from the Head Unit.
