amp for vandersteen Quatro maybe vandersteen 5a

Yup, what everyone said:
Ayre
ARC
(I assume Aesthetix is also a good choice as Vandersteen has paired with this at several shows)

Yes, I've heard the upper end Vandy's with all the gear you are listing and they all sound great. Heck, the AR Ref 75 with AR pre was about as good as it gets one of the times I heard the 5A CT. It just was musical, dynamic, detalied without anything getting in the way. I probably posted that above in this thread, but it's still that good in my head. All of us who were listening couldn't belive it was a 75 watt amp doing that.

The main portion of the 5A is tube friendly- most of our customers use our MA-1s on there to good effect.

Richard LOVES the sound of SE and tubes. Yes, they mate so well from 100 up and then their own built in amp takes over.

I have used many different amps with Vandersteens over time: Levinson, Belles, McCormack and Conrad Johnson

For me the CJ's are the match I prefer and have been using with Vandie 5A's for many years. Very listenable