Going from the Adcom GFA 555 ii to the Bryston 4b SST or SST2?

You are likely looking at 2nd hand. Assuming you are running single ended(555ii), purchase an ADA PF201. A real sleeper of an amp....and I know.

Thanks for the advice everyone! Will explore other brands as well. Looking forward to the research

How would the 3b sst2 be? I do nearfield listening anywhere from 50-86 spl/db.

The 3B SST2 has plenty of power for your speakers that are not a difficult load for an amp. 

@solartea123 Depending on your preamp/front end, it might be beneficial to upgrade further up the chain. What goes in, comes out. Just a thought.