I have a headunit (non pre-amplified), without amplifier (connected to my two stock front speakers), and my two Pioneer (ts-a6991) 460w rear speakers. They sound kinda weak and with distortion (specially the front ones), I adjusted the FADER to hear more the rear speakers, but my question is... will an amplifier convert my powerful rear speakers into a deep/powerfull bass speaker? or not too much?
NOTE: I am not comparing this speakers to a subwoofer, but will i still get mucho bass?
Any round speaker will also handle more power and give greater SQ than an ovular or square shaped speaker.
6x9's really aren't meant to have a lot of bass, well not good sounding bass, just crappy "boom boom" bass. You'd be better off with some components. Even at that though, like Ty said, your speakers are not meant to reproduce the bass from music and tones in manners that a subwoofer would.
Pioneer Deh-2770MP (use my 2 stock speakers in front, and my 6x9 rear speakers WITHOUT ANY AMPLIFIER only the pre-amp channel from the HEADUNIT) an XM-502Z amplifier (120w rms x 1) and a 12" XS-L121P5
IMO - for the average consumer a good pair of 6x9's adequately powered can provide more than enough bass.
For all the 12v geeks on these forums?? No, probably not going to cut it.
I remember back in the day when my brother put some yamaha 6x9's in his car powered by a nice 50x2 PPI. I lost count of all the people who asked him what kind of subs he had.