Best SS integrated for Pro Ac Response 3.8

I am now looking for a new SS integrated amp for my Pro Ac Response 3.8 speakers (great, great speakers!!!). I consider Jeff Rowland Concentra II and Gryphon Callisto 2200. Does anyone has any experience with those two amps?
I have read a few comments that stated that ProAc and Rowland go well together. I have a Concentra II but I have never heard it with ProAc's.

I am extreemly happy with the Concentra II!
I have heard the Response 3.8 with many different amps, both tube and SS. By far the best sounding were a pair of Essence monoblocks. They are expensive but can be found from time to time on Audiogon. Add them to your short list, they are THAT GOOD.
I have heard Brian's Concentra II (above) and it is a brilliant piece of audio gear.

It is one of those rare pieces where you forget about the stereo and the music gets transported to your living room.

We have both listened to many pieces of gear on his system and the Concentra is my choice by a margin of about 2 to 1.
I sold Brian the Concentra II, and I have to chime in say that the Concentra II is one of the best amps (and preamps for that matter) I've ever heard!! It ran Sonus Faber Electa Amator II's in my system (maybe similar sound to the Proacs?) and it was fabulous. I still miss it!!
I think that the VAC avatar SE integrated tube amp works well with the Pro Ac´s speakers, like the soundstage they produce.
I have had my Concentra 2 for many years, originally paired with Proac response 2.5 and the sound was heavenly!

It is a wonderful piece, and sounds incredibly musical with any speakers I have used.  Right now paired with rebuilt Quad ESL57, and that combo is hard to beat.  One of these days I'll pull out the Proacs again.

I have owned a first generation Concentra for many years, and have never had the urge to replace it. Fantastic amp.