Nice
When I got my new (used) speakers it came with a Yamaha HTR 5950 receiver. I've had the speakers hooked up to my Sony STR DG510 just to see the difference between the new and old speakers. There was a big difference in the speaker sound but nothing compared to when I switched the Sony for the Yamaha. If this is an indication of what everyone else is like compared to Sony I wont ever be going back. After hooking everything up and switching on I was astounded in the depth of the surround, clarity, and power of the Yamaha. After switching the speakers and using the Sony I had to turn up the Bass and Treble, the sound just wasn't sharp or as clear as I thought it should be. Not with the Yamaha, it could switch to 6ohm for the speakers and I don't know how much that had to do with the difference but it was night and day different. The Yamaha has a lot more adjustability and the owners book is just that a "book" with good information. The Yamaha receiver is a little smaller than the Sony buy yet weighs more. I guess there is a reason why Sony's are so cheap compared to others.
Sounds great, glad you saw improvement.

Now
just wait until you switch from Yamaha to Marantz 
Seriously though, I have been very pleased with Yamaha receivers and saxaphones and keyboards and digital pianos I have owned.
Product summary
The good:
The Yamaha HTR-5950 is an affordable, 110-watt-per-channel 6.1 A/V receiver that offers component-video conversion, front panel A/V and minijack inputs, an onscreen display, and compatibility with XM-ready satellite radio tuners as well as Yamaha's optional iPod dock.
The bad:
The HTR-5950 lacks automatic speaker calibration and HDMI connectivity. Its three rear-panel A/V inputs may be too limiting for many home theater setups, which often feature four or more A/V sources.
The bottom line:
Yamaha's midprice HTR-5950 A/V receiver might not have the most up-to-date features lineup, but it's a solid performer.
Specifications:
Product type: AV receiver; Sound output mode: Surround Sound; Amplifier total output power: 540 Watt
Concerning speaker calibration, get a $50 Radio Shck digital SPL meter. It works great!
Good luck!
MidCow2
P.S.- Sony makes good TVs
