Yea I know they are 4ohm. That Yamaha has a very good amp section and would do for awhile, but when your talking 8-10 G's for speakers you know you'll be looking at more headroom sooner, rather then later

. Since your looking at the JL's, then IMO there's no point in buying full range speakers, go with monitors and get 2 JL f 112's.
PS: I read your question @ AVS but posted here instead!

It's easier to spend other peoples money, then my own. LOL