Help deciding on an amp.

For $1200 Id really try to grab a MCA 50

Mine were amazing with a PSE studio IV. Any slightly warm 100 watt amp should do fine. The threshold 400A is one of my all time favorites. However, it is very old and when they have any problems at all, it is a disaster to fix.
You could look at Anthem over the Proceed. I'd also look at Sunfire.

Bryston

Your setup is well balanced. I don't understand why you want to change out
the amp. Is there something wrong with it? IMHO, I don't think the amps on
your list are better than the MC2105. They sound different, yes; but not
necessary better.

If you get tired of your amp and want a different sound, that is fine. But than
you need to audition them yourself and decide what you like best. Buying
something based on other people's taste will probably end up with
disappointment, especially you already have a well matched system from what
I see.

I was curious to see what was going on with BEL (Brown Electronics Laboratories), so I did a search and I couldn't find a website on them, so I'm not sure what's going on with that Company. I did find some info below, however.

http://forum.audiogon.com/cgi-bin/fr.pl?aamps&1215778523&openfrom&1&4

Great Sounding Amp! Are You Feeling Lucky?

CORRECTION: I'm sorry, I meant to type the "BEL 1001 MKII Amp," not the 1000 as stated above.
.

I haven't listened to the Threshold, or Nakamichi. Is Hafler still around? I think you could do better than Hafler and the B&K mentioned above.

The Proceed Brand, is out of business and may present a problem with service/parts or repair.

I had preferred the Proceed HPA-2 over the Proceed Amp-2 that you mentioned.

Out of this list I would probably go for the Classe DR-25 and then the Proceed HPA-2 (if service may not be a concern), and then the Bryston 4B-ST, not the Bryston 4B.

I hate to confuse you more, but I would also consider; Parasound Halo A21, McCormack DNA-125, McCormack DNA-1, Aragon 8008, Aragon 4004 MKII.

I've heard good things about Odyssey Amplifiers on Avguide.com by Jonathan Valin from TAS., although I've never heard the stuff myself.

After righting all of this, I realized that I forgot one, and it happens to be a really good one, and it's on AGON right now for $850 If I were in the market for a used AMP for under $1000 then I would buy the BEL 1000 MKII.

I'm sure we're going to get a lot of opinions here. Let's see what the consensus is with your Vandersteen 2CE Speakers, which are lovely by the way.

Happy Listening!