Amp upgrade from Bryston 4B


I currently have Thiel 3.6s main speakers driven by an older Bryston 4B amp that has been a good match. I have been considering upgrading the Bryston 4B amp to used Bryston 7B mono blocks(?) However, the Bryston 7B amps have had mixed on-line reviews. Any other recommended amp upgrade recommendations in the $5K used range that would be a good match for the current Thiel 3.6 speakers and potential future Thiel 3.7 speaker upgrades?

OTHER EQUIPMENT: I am setting up a 5.1 surround system with an existing Rotel 985 5 ch amp to drive Thiel SCS4 center and Higherplane 1.2 rear surround speakers. I am currently using an Outlaw Audio 995 processor in bypass mode for 2.1 stereo listening.
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If you like the sonic characteristics of the 4B, the 14B SST Squared is magical in its combination of power and staging, detail and depth. I have heard them both sound quite excellent with THIEL.

Thanks Dave
"If you have a Pass Labs dealer in your area, have a listen and see."
Unfortunately I do not have a dealer locally for auditioning. I am interested in either the 7/14B SST2 or the XA100.5 for my Magnepan 3.7´s.
Can you get to one out of your area? Pass Labs is a nice friendly company that'll steer you in the right direction if need be.

Imo, the XA100.5 will blow away the 7/14B SST2.
Thanks for the responses. The pre amp is currently a weak point in the system. After spending the wk end using the Outlaw Audio processor in bypass mode for 2.1 listening I switched back to my passive preamp which is a big improvement in clarity and much more pleasing sound. I will eventually replace the Outlaw Audio processor, but 5.1 surround listening is not a priority. Therefore, I am concentrating on upgrading the stereo components first.

My current Bryston 4B amp with the passive pre amp has been a good match for the Thiel 3.6 speakers, but would like to upgrade. A bryston pre amp with a bryston amp has had good synergy reviews. The bryston pre amps have a stereo selection that is not a true bypass for fully using a surround sound processor.

Some of the fd back on this thread has indicated that a bryston 14b amp would be a good match with the Thiels. My understanding is the 14b amp is essentially two 7bs combined in the 2 ch amp. Any reason not to lean towards the 7b mono amps vs the 14b? Some of the other recommended amps with are also worth considering with a pre amp upgrade.
I believe some say the 14B sounds better. Don't hold me to that, however. According to Bryston, the 7B has more capacitance than the 14B, plus you can run shorter speaker cable, always a plus in my book.