Can't speak to the 6T's, but I have the B135 paired with Gershman Acoustics Sonogram speakers and love it - probably the last amp I'll buy.
It should have no problem with the 6T's because they are a little more sensitive than my Sonograms.
The image achieved by the B135 is superb and very large - melts away the walls of your listening room.
Dynamic, detailed, crystal clear sound, very neurtal clear, etc. etc.
Plus a 20 year transferable warranty - can't go wrong
My B135 replaced a Naim 5i (mk II), which I loved the sound of, so replacing it made me wonder if I'd like the Bryston sound - turns out - I love it.
The B135 is basically separates - they are just in a single case :-)
Regards - Steve