I'm in the camp that electronics sound the same, provided you run them within their limits. So, I dismiss any claims where someone says "my Yamaha sounds bright" or "my Marantz sounds flat" or any nonsense like that. I highly doubt you'll hear any difference between those brands if you were DBT, so, if you were going down the road of purchasing a new receiver, you'd be best served looking at desireable feature sets (such as room equalization that Adam mentioned, or preouts), GUI interfaces, and ease of use instead of trying to figure out which one has the best sound quality.
Sound quality is primarily driven by a.) your speakers b.) your room's interaction with said speakers and c.) source material quality (CD's vs low quality MP3's as an example). So, instead of dropping $1000-2000 on a higher end receiver, you'd obtain much sound quality by spending that money on better quality speakers.