If there is ventilation holes on the top of your receiver, you could be restricting air flow by having something covering them.
In my opinion, receivers aren't musical, warm, bright, as some may describe. They are designed to have a flat frequency response from 20hz - 20khz based on required guidlines. Unless you have one of the DSP modes turned on, they won't have any sonic coloration of the sound.
Denon also have a few online etailers that sell refurbished models, like Dakmart. Their website has a link to show you all the online etailers. I just purchased a brand new 3808 from 6ave.com for about $100 higher than a refurbed model. They also offer additional discounts if you tell them you are a member of the AVSforum.
You don't have to get Denon, I just like them because they seemed to have the most advanced Audyssey room correction offerings. Onkyo is good as well. I think Marantz also makes nice equipment..
