Upgrade amp for Infinity RSIIs

I have used an ADcom GFA-555 and a Forte 6 with these speakers. Thinking about upgrading the Forte with Jon Soderberg or getting a different amp. Have a little over a grand to spend. Any suggestions?
I use an Anthem Pre-1 tube preamp and a Jolida 100a (with TJ Full Music tubes)cdp.
I listen to full range of music: jazz, blues, classical and classic rock. use vinyl and cd.
I was considering the Wyred 4 sound St-500. Any input would be appreciated.
I had owned Infinity RSIIa's for almost twenty years, from new. I got tired of them and sold them for parts!! (the EMIMS alone are worth more as parts than the whole speaker was)
Anyway, The Forte is a good amp. get it upgraded. (I am just selling my Forte' 4a I have had for about 17 years!
Good luck.
(I now use a Bryston 4B-SST2 and Magnepan 3.6s)