My "man cave" sounded great until I added a pair of subwoofers. I purchased REW (Room EQ Wizard) and that microphone, and got 10 bass traps positioned as well as I could. I could probably use two or three more bass traps in that room, but 10 was pushing the "WAF" meter as far as it would go. I'd say I've got the problems with bass about 95% solved (before installing the bass traps the room resonated one particular note, no matter what the bass player was playing, that's pretty much solved), but sometimes when I'm playing music with lots of low frequency dynamics, it sounds like the room can't handle that much low-frequency energy.
The more people I ask about electronic room correction, the more people I find who say "stay away" from it.