Not sure how good your grasp of this is, so if you already know this don't think I'm trying to send you back to pre-school or anything.

Anyway, db's are kinda crazy things, and at 106 db/1 w 'hounds speakers are roughly 40 - 50 times more efficient than 'average' speakers. So when he has 10+ watts driving them, well, he's still got lots of poop in that system where it matters, at the human ear.

Very roughly, every:

10 db, x10
5 db, x3
3 db, x2