I'm contemplating getting the AS5 stand, but they say that the shelf spacing is fixed at 7.5". As my receiver is 6.8", this would seem like inadequate space for ventilation. Does anyone have an opinion on this??? Would it be possible to leave out one of the shelves during assembly to garner more space?

There may be just under an inch of space above the receiver, but won't the back and sides be completely open? If so, I should think that would be plenty of ventilation. (Unless your receiver gets really hot.)

I've had the AS5 for a couple of weeks and love it. I have about 2 inches above my Denon 1603, but I think there is plenty of circulation moving around the unit with the open sides.
You certainly need to use all the shelves for installation.
You could always consider putting it on the top shelf.

My Harmam/Kardon AVR325 turns on its very loud and annoying fan after a couple of hours when stuck anywhere but the top shelf of my AS5. It never actually gets hot enough that it shuts itself off though.

What do you have running off of the 325? I've never had the fan turn on on my 525 (but I'm only running 2 speakers) even though it's in a very restricted area (this should change in a month or so, when I finally finish my new EC.)

I've got a VP100 as center, a pair of M22Tis at front, M2is as surrounds, and either Paradigm Titans or EPI T/E 70s set up as multi-room speakers (I dont remember if I had the Titans there yet, they replaced the EPIs).

So a full load, then. How loud?

I typically use the -40db to -25db range depending on the source, not terribly loud in other words. It should be noted that the stand I was using prior to using the AS5 had similar clearance, but I did not have the same problem with it. I think it may be that the thick black enamel on the AS5's shelves just build up and reflect back too much heat.

Hmm. Interesting. Well, YMMV. Who knows, my new EC may have a similar effect on my 525. God, I hope not...