I just bought a pair of 20.7 Magnepans.
(now that was a real upgrade!!
I have a Bryston 4B-SST² I used with my previous 3.6 Magnepans.
(The 4B-SST² is all the power I need, as I generally play music at 50dB up to 70dB to the very highest peaks 80dB play opera areas.. So I do not need more power than 500watts per channel, even with 20.7s.)
I am perfectly happy using the 4B-SST² with my 20.7s.
(someone who knows said I did not need the amp now, I could use that money on other more important stuff)
I spent the money I almost spent on cubed amps on a really worthwhile $7000 DAC/SACD player instead. (which I needed and can find worthwhile, way more than a slight upgrade in an amp)
There was a thread about the 17B3 preamp, and someone was saying they got it to replace their BP-26.. No way would I go backwards for a cubed anything.
(I like my phase switch!)
Anyway, I am perfectly happy with the previous generation models.
(the BP-26 just got TAS recommended anyway)
IMO you might have upgrade-itus. In which case you might find your actual weakest equipment, and upgrade that instead.
I know saying do NOT buy a new Bryston on the Bryston circle is heresy!
But someone has to say it.
Things I need before I go for cubed amps (7B3)..
An ultrasonic record cleaner
A Rega RP-10
A 'really' better phono box like a $12500 BAT?
The BAT would really be over the top. but never know, it might be just what I need.
.....
Anyway, the amp might be worthwhile if you had everything else at the top of what you can do. If not.. look around.