As I am waiting on the 990 to be delivered, I went ahead and downloaded the owners manual to get a head start.
The manual states 6" clearence on sides with an open back. My question is, how hot/warm does the 990 run? I was uner the impression that pre pros don't creat any heat.
I do run 3 fans in my equipment rack, I'll only be able to get 1 1/2" on sides and 2" on top of 990.Heat hasn't been a problem in my rack even though my equipment runs very warn. As it is, everything is cool to the touch.

My 990's faceplate is about 1" behind a glass door; there's maybe 2" on each side, 3" back to a cardboard rear panel which was pushed out to the room wall behind it to make room for the cables (on account of this unit is almost too deep for its space), and 6" on top. When it's running the top is warm but not hot to the touch. If the heat is degrading my unit's performance it must be mighty subtle because it sounds fine to me.
With your fans (quiet, I hope) I don't think you'll have any problems.

Thanks;
I do have doors on the front , but with small vent holes top and bottom.My amp runs hot, but with the fans stays cool to the touch. Fans are very quite.
I'm thinking it should be OK, I just needed reasurence from a 990 owner.

For what it's worth, I've got a closed front, about two inches clear on the sides, and a back that is cut out only enough for the 990's rear panel to poke through for wiring purposes. There's a couple of inches clear above it, as well. The amp (Model 7500) is in the same sort of enclosure one shelf below, although there's about a foot clear above the amp. I think you'll be fine.

In my last message I guessed at the space around my 990. I just measured: it's two and a half inches on each side and 4" up to a solid shelf, 1" in front and 3" in the rear. These are slight changes that don't change the point that it runs fine. Not to worry, Bill O.

My 990 is in a very tight space in my cabinet, I have had no problems.