few other factors to take into account as well
How big is the room? what music are you playing?
Location. How warm is it where you live. Do you have AC on in the room? Is it on top of a unit( knowing you that is a dumb question )
Some say the Nad gets warm. And when I had it upstairs for the first few weeks I noticed it as well. But upstairs in my place with no AC in the middle of summer was warm. Now it's downstairs, in it's own 7.5'x4' closet which is on concrete with no sub floor which also keeps the room cool. I purposely left the sub floor out of this closet for that reason. The Nad is by itself with nothing around or above it for several feet. It's also ventilated to the outside so I have probably the best conditions possible and the nad doesn't even get warm after several hours of crazy crazy volume. Funny though that the fans are still always on.
How loud is the fan in the 4600? Not that it matters to me.
I know sound is a relative thing, and can heavily depend on what your eq is set on, but next to the nad, any comments?
There is a thread at avs for the 4600 as well