Bryston and Maggies are a match made in heaven (which is why the factory demos Maggies w/ Bryston amps) But Maggies are also very power-hungry so the 3B probably won't cut it. 4B at a very minumum, 7B should be quite adequate.
On the other hand, if you can afford a 14B, then you might want to consider a little bit more refined amp (Krell, Rowland, Mark Levinson, etc.) or bi-amping with a 4B on the bottom and maybe a toobie for that ribbon.
On the other hand, if you can afford a 14B, then you might want to consider a little bit more refined amp (Krell, Rowland, Mark Levinson, etc.) or bi-amping with a 4B on the bottom and maybe a toobie for that ribbon.