Is a Bryston 3B SST2 enough for Magnepan 3.7i or 20.7?

Thank you Al,
Ok then the idea of bridging just went out the door...🤗
But To make sure I got this right:
So what you are saying is that the amp should also close to triple it’s power into the 2 ohm load (in the bridged mode) or about 3000w, in order to sustain the same increase of 6 dbw?

@Lucidear, no, I wasn’t saying that. When I said ...

So unless the amp is known to perform at or close to its best when driving 2 ohms in stereo mode I would not count on it providing good results when driving Maggies in bridged mode.

... I was referring to the amp being known to **sound** close to its best when driving 2 ohms in stereo mode, since in bridged mode it would "see" a 4 ohm load as 2 ohms. Implicit in that statement, of course, is that the amp should be able to function in a reasonable manner when driving a 2 ohm load in stereo, without overheating, fuses blowing, or self-protective shutdowns being triggered. The 2 ohm power capabilities you listed for the specific amps suggest that they would meet the latter requirement, but say little or nothing as to how they would sound in doing so.

And regarding how the amp would sound in bridged mode when driving 4 ohm speakers, the fact that Simaudio does not appear to provide a power capability specification for bridged mode for anything other than 8 ohms is not encouraging. (Also, btw, text on page 11 of the manual indicates a capability of providing 800 watts into 8 ohms in bridged mode, which conflicts with the specs page of that same manual and the specs shown at the website, which indicate 1200 watts).

Now understanding that these amps could sound different from one another, my question is:
Do these larger transformers, more capacitance etc. etc. have a noticeable affect on these Maggies even though the indicated output wattage of all three are very close to each other ?

While I certainly appreciate your attempts to determine these matters analytically, and if everything else is equal those factors are of course **potentially** beneficial, as a practical matter there are so many design-dependent variables and unknowns involved that listening, and/or finding credible reports of relevant listening experiences, is probably the only way to tell.

Best regards,
-- Al

P.S:  "355@4/500@8" in your post should of course be "355@8/500@4."

Al
Thanks a bunch for all the info, I'm pretty sure I got them...
And you are correct on the last point, it was a typo on my part.
All the Best

So you have a very inefficient speaker with a low ohm loading on the amplifier. I believe that many amplifiers distortion profiles change for the worse as they get driving low ohm loads, it requires a stiff power supply or a switch mode power supply. Maggie's are awesome though in every sense when properly driven, and properly placed in the room, pulled significantly away from reflecting surfaces as bass waves will screw with them. THEY CAN IMAGE LIKE CRAZY! Good luck!

Random memory trace just surfaced. 

I used the Bryston 3B SST on one pair of Tympani II, I believe it was, and a 4B SST on another pair of Tympanis, running in parallel. Could not tell the difference at moderate listening levels.

Anthem's PVA 2 is comparable to the Bryston, but still not really what you want to run the Maggies.  I would say step up to Anthem's MCA225 $1999 Retail 225w x 2.  More power and more open sounding than comparable Bryston's.  Bigger money - go to the Anthem P2 $4500 325w x 2.