TX-SR503 $269.99 (at circuit city)
TX-SR602 $347.81+shipping (onecall.com)
TX-SR702 $547.81+shipping (onecall.com)

I have a one bedroom apartment so I can't really blast my speakers, but I want a good quality sound. Is there a huge sound quality difference between these or is the price increase due to the features? I know the last two have the auto setup which I like but is there are real audio quality difference between the two? Thanks