Merch, if your setup is going to be 5.1 without back surround speakers it probably would be a better idea to use QS4s for the surrounds so that their very wide dispersion can better handle the surround duties for the entire room.
As to a receiver, unquestionably the 540R is very fine, but it does seem to be a bit pricey. Units available for around $300-$400 from Denon, Onkyo, Pioneer, Yamaha, etc., might be more cost effective.
Edit: well, if you're willing to go as high as $600, a great buy at this point is the factory refurb Onkyo 705 for about $530 plus shipping from
Accessories4less .
