Want a 5 channel amp that can drive 4 ohm loads

I am planning to go to surround sound (probably a 5.1 due to the size of the room) and will probably add Totem or Rega speakers for the rear and center channel. Both are 4 ohm speakers and my front mains, Royd Doublets, are 6 ohm speakers. Can anybody suggest a decent pre/pro system for around 2500 dollars that could drive these speakers.

Thanks!

Dave