I don't disagree with Walter, power IS a good thing, but there is a point at which you are no longer adding any benefit at all. Having more than you need is definitely not an issue, but its also like having 1000HP in a Miata. You literally won't use more than a fraction of it. IMO 200W is about the sweet spot, so to speak, rather than the entry level point, but obviously depends on your sysetm (room size, listening habits, speakers, etc...).
I also agree with Pyrrho, adding power won't change your sound nearly as much as speakers. Since you are happy with the speakers, the only thing more power is going to add is SPL = you can turn it up louder with it remaining clear. It does seem like you are looking for more power than a typical AVR. Watts aren't exactly all the same though. 125W from an Outlaw amp is not the same 125W you will get from a typical AVR
That said, the 9s can likely handle plenty of power, so 200W should be good. When I said crossed to the sub, even with the 9s being big, you are wasting power if you run them full range; bass is what subs are for so let them do the heavy lifting. My room is quite large (~25x30 high vaulted celings) and with 200W I can literally shake the walls. They aren't big speakers either
Click on My HT in my sig.
To the subs, no offense intended, but you wouldn't need to spend that much to improve on them. AH reviewed the SW115 and gave it a positive review, so I'd guess these are decent too, but I'd still call them the weak link in the setup and would put more into quality subs than going overkill with the amp (like 500W).
Room acoustics is another factor for sure. YES, his room being treated can make a significant difference in how things sound. Getting yours properly setup and doing a few minor treatments should also get you very good results though. Dual subs need far more specific calibration than a single one otherwise you can end up with them fighting each other. Running the mains large with two subs will also potentially degrade the sound.
