well thats an interesting question.. I have been a bass head for years, use to do SPL comps. and this is only my second time running 10's (the first time I ran 6 of them. lol) this is the first time i have run a speaker combo in a sound quality fashin. I just installed a new set of round solo's (7 year old speakers brand new) had them laying around. it sounds good just its not what im use to, it blends in nice with the stock bose speakers, I think i might install one of my 12's i have to see which i like better.. 10's give you a nice crisp puncky sound while 12" sound more full, deep and low. In my opinion 1 10 would be to quiet unless it was a w7.. 1 12 would be nice.. it all depends on what kind of music you listen to.. more rock and roll stick with a 10" more R&B, Rap, Pop, and some rock. then the 12" will sound better.. (hold out the bass notes a bit longer).. I use to work ata car instalation place so i still have a bunch of speakers laying around that i have used in the past so i have the luxury of swaping set-ups out with an amp that will handle .5 ohm load and deliver a constant 1600..