Bryston vs MBL

" Bryston appealed more due to power for dollar, warranty and still have decent looks.  MBL more for curiosity and supposedly high end exotic level amps.  just really want to hear how they would sound in my system.  I am a little concerned on how the Brystons can be had second hand for almost half price?  the 7b3 are current models and asking 7k price now ."

I know you're not going to want to hear this, but I would say buy based on sound quality, not price. I would even go so far as to say, given the level of your pre and speakers, you're crazy if you do it any other way. Especially when your temporary amps cost 7k.

Cost is obviously a factor here since you're not getting the amps you really want. You owe it to yourself to take the time and get it right. Also, if you've never heard the MBL's in your system, I see no reason to expect better sound quality than from some of your other options. Its not at all uncommon for someone to prefer a less expensive component. For example, in my own system I was looking for a new amp(s). I was willing to spend 20k+ if I had to. In the end, I went with 2 Ayre V-5's that cost less than half of my max budget. Why? They were the best sounding of all the amps I demoed. 

" Pass Xa 200.5 is stretching the budget but could do if i only knew it was signficantly better than the 7b3."

That's the problem. There is no one is better than the other. If you listened to both amps, you would see that they sound very different. The designers take a completely different approach as to how they do things. Some people will like the Bryston, while other will pick the Pass.

" Bryston appealed more due to power for dollar, warranty and still have decent looks."

You need to be careful with power amp ratings. There's no standard that everyone has to go by. Each company does it their own way. If you took 5 power amps from 5 different companies, all rated for the same amount of power, and measured them all the same way, you would get different results for all 5 amps. 

Just to give an example, I used to have a Pass amp that was rated for 40 watts/ch. When I put it next to my Krell that had 250 watts/ch, there wasn't much difference. The bass was a little tighter, but you would never guess that you were comparing a 40 watt amp to a 250 watt amp. 

If you live in the US and don't have any local dealers, give The Cable Company a call. They should be able to send you some amps to demo. They carry Accuphase, BAT, ASR, Luxman, NuForce, Auralic, Bel Canto and probably a few others that I'm forgetting. Out of all those brands, I would want to try a solid state BAT. I can only guess, but I'm pretty sure you would prefer a BAT over the Bryston. Bryston is a good sounding amp, but its a high feedback design, and they don't come alive with music when compared to amps like BAT. 

You haven't mentioned tubes, so I'm assuming you're not interrested. But if you would consider tubes, you can get something like an ARC VT-200. Needless to say, it would be a good match for your preamp.

" Another high power consideration for you is the Aesthetix Atlas. Underappreciated in my opinion, and resale units seem like a bargain. I own a stereo Atlas amp."

Its funny you bring the Atlis up. I know its a good amp but I won't recommend anything I haven't heard myself. But it is tempting, especially since I have a Calypso. Have you compared the Atlas to Ayre? I have 2 V-5's in my system now and I haven't heard anything that makes me want to upgrage. Just curiouis. 

" I bought it on a recommendation from Audioconnection as a match for my Calypso preamp."

Say no more. John R is on another plane of existence compared to other high end retailers. In my opinion, AC and The Cable Company are the 2 best audio stores in the US.