I would get rid of the 6x9's, get more speakers for your upfront and put them in desireable locations, front doors, a pillar, centerconsol etc. I have to Fi SSD's and i had a 6.5 speaker for vocal in each door and the rears did nothing. I added them upfront and it made all the difference. So now i had 2 6.5"s in each front door for vocals and ive learned vocal speakers in the front and subs in the rear. I love it that way. Sounds the best to me also. Try useing just your front speakers with the subs on a lower volume to see if you like just the front fill without the 6x9's. Then upgrade your fronts and or add more to keep up with your subs.