Robert,
I'm getting the same "warm" feeling about this amp but I don't have the kind of high end gear that you have to compare it to. It does seem to be sounding better but I'm told that with solid state amps they don't really have a break in period. It's more just getting used to how they sound once you have them. I don't know about the theory but I am really enjoying this thing. It's bringing out a lot of "sound" that wasn't there before. I was just listening to a Yo-Yo-Ma CD in 2 channel and you can actually hear each time he takes a breath. Never heard that before. Neat! And then threw on some Glenn Miller big band stuff. That really made the Axiom M80v2's I'm using show their stuff. And I don't even normally listen to this stuff. I'm a folk/rock guy (Jackson Browne, Joni Mitchell, etc.). Needless to say, even with the scratches, I'm starting to smile more and more about the 990/7500 combo.
About the scratches, I also talked to Outlaw (Steve) and referenced your issue. He said he was aware of it and they were very concerned. It is great to deal with people who believe in great customer service. I mentioned that in my case I wasn't that concerned because the scratches were on the side and with the amp in my rack you didn't see them. He called me back a few minutes later and said that they they were going to figure out something to make it right with me anyway. And I didn't even ask for anything.
The other thing I like is that I'm very much a novice at this stuff, and whatever I've asked him, regardless how dumb a question, he hasn't talked down to me at all. He just seems just genuinely interested in me making the most of this purchase. What a great way of building customer loyalty....
Regards.