Recommend a SS amp for my new Vandersteen Quatro CT

I did not mention Bryson because I have zero experience with them on Vandersteen's. I am NOT a detractor - I have a good friend with two pair of big B&W in well designed rooms running them - try it !!!!
Good call on service checkup of the 100.2 database says something like 1999 thru 2003 production so a refresh might be good.
again - excited for you !!!!

IMO
you are putting the $ in the right place - I think you will be amazed how good the ARC gear sounds
i use a REF5se
who is setting up your Quatros?

I have heard 5a with Quicksiler and can attest they are quite good.
i believe the demo system at CES this year had Brinkmann powered Quatros - said to have been lovely !!!

You are in for a real treat :-)
IMO either amp you own excellent place to start - just make sure to properly adjust Low Pass filter DIP switches when changing amps. !!!!!
i have heard Quatro CT at many dealers across USA  with Ayre, Aesthetix, Rogue, ARC ( Ref 150, HD220 ) as well as VTL. frankly all were outstanding - I have also had a REF 75 at home running my 7 mk2 and can attest that it is one sweet amp !!!
i have an Ayre VX--R Twenty, you might give that a try - I think Richard and Charlie are pretty aligned on many design considerations and philosophy. 
importanly the Filters are RCA or balanced but not both so plan ahead there.
the Aesthetix amp has built in filter should you go that route.
where are you located ?