Adcom upgrade ,or stay put ?

I upgraded a while back from a gfa -535mk2 to a Bryston 3B.
The step up was tremendous. The sound field seemed to extend about 5 ft closer to me and the amp was so much "quicker" than the Adcom. I've since moved on to mono tube amps but I remember being very happy with that Bryston amp, esp. for live music.

I hope you're in an area where you can audition lots of amps. What Charlie123 says about Bryston is definitely true, but Adcom has not stood still since the GFA-555. Their new MOSFet amps are far faster, more transparent, liquid, linear, sweeter, and dynamic than their old bipolar amps. I have a GFA-7700 multichannel amp from 2005. It's a budget multichannel amp and has already been discontinued, yet it's worlds better than what Adcom was making in the mid'80s.

There are lots of good amps now and at a wide price ranges. The budget high-end amps are better than ever before. I'm using an Onkyo A-9555 in my 2-channel music-only system, and it's worlds better than what you could get for $2K just a few years ago, yet I got it new w/warranty for $484. Another brand to consider at the budget-to-mid-level high end is Parasound.

And the better amps, like Bryston, Classe, Ayre, and then on up to VTL and the like, are simply stupendous.