Amp Upgrade Advice

Recently decided to move up to Magnepan 3.7i's from my 1.7i's. Thinking about upgrading amp to go along with them.

I'm currently using a Threshold S/200. Relatively happy with it, but curious what else is out there. I've read enough about the benefits of getting north of 400 or 500 watts/channel into Maggies that I'd like to try that.

Budget would be around $6,500 (used or new).

If going new, I'm thinking:

• Sanders Magtech
• Bryston 4b3

If going used, I'm thinking:

• Bryston 7b3 (or 14b3, seems like they perform pretty identically)
• Pass Labs X250.8
• Parasound JC1s

Any thoughts? I like the idea of getting a used 7b3 for approx the same price as a new 4b3, and still having 15+ years under warranty... Also curious about pass labs. Unfortunately it's a little harder to get a hold of used stuff to audition...

TIA

ps
the rest of my system:

• Michell Orbe w/ SME V
• Benz Micro Wood (low output)
• Spectral DMC 10 preamp/phono
• Threshold S/200
• Magnepan 3.7i's