More power or better quality power?

I use a 120 watt NAD integrated and a pair of Sonus Concerto Monitors (Home version), and a REL stadium III for the low end. I am researching new integrateds because my System sounds lifeless. My car system sounded much the same before I added a higher power (twice the wattage) and higher quality (3 times the price) amp. The difference was night and day. So I am wondering, do I need more power for my home system, or do I just need better quality power...or worse yet, BOTH! My room is pretty large (18 by 18 give or take, plus a high vaulted cieling). The system is tucked in a corner and i listen from about 8 feet away on axis. I listen to everything, but mostly rock. I was considering a 100 watt Primare that is on audiogon right now. I was going to go Plinius, but I think with warm speakers, and warm cables (cardas) That might be just too much warmth :)
Low level quality of sound is important because I do no live alone and don't want to need to crank it to get a good quality sound.

So, is bigger really better, or is it it the quality?