I've posted my experiences elsewhere, but to sum up, I ended up with the AVM20 (v2) after going through two Ref 50's.
If you can find a Ref50 without the noises, then it's truly a great product. I really wanted to get rid of the noise and keep mine. But the two I had in my setup, and the several others I auditioned in various store setups (with latest software), all had the whine. After speaking to someone at B&K, there was no indication of any "fix" in the plans.
To me, any audio product in this price range should be void of the noise floor I heard on the Ref 50. BTW, I found that I could hear the whine with the volume set at *any* level (even with mute engaged), when the room was quiet enough and from my normal listening position. Could it be that I'm more picky, or my ears are more sensitive than other? Yes.. I'm unsure whether this is the case, or whether there truly are "noise free" Ref 50's. I know that all the ones that I listened to sounded the same, and a person at B&K told me that some "processor noise" was completey normal, and there's nothing to fix.
Except for the remote control, I'm 100% satisfied with the AVM20. Sounds just as good (if not better), and there are no "noises". Both have features that the other does/doesn't, which will appeal to different people in different ways. The biggest feature differences (for my needs) are the very nice Presets on the Ref50, versus the better Bass Management on the AVM20. Minus any noises on the Ref 50 and the remote control of the AVM20, it's really a toss-up between the two. To me, no feature is worth dealing with sub-par audio specs. Both $2k and $3k are a lot of money for a box. In my opinion, saving $1k is nice, but it doesn't make the "product" any better. I didn't audition the Rotel, so I can't comment on it.
Many dealers have a money-back return period of a week to 30 days. If possible, the best thing would be to get all three units and try them out in your setup. Don't trust anyone, but yourself.