Looking for a very good integrated solid state amp

My system consists of:
Castle Stirling IIs,made by the original Castle firm in England, 91 db,
Rega Brio R integrated, Rega Dac, Musical Fidelity V Link 192, Atlas cable, Macbook Pro.
I love the Castles but I feel the amp should be of higher quality to get the fullest out of them.
My budget is $3,000 or so.
Anyone have any experience with:
Perreaux Audiant, Musical Fidelity M6I, Ayre AX7e, Linn Majk I, Sim Audio, etc.
Thank you very much---
Sugden A21SE used should be considered. 30 wpc Class A. Not found a speaker it would not drive well (I'm sure they exist) and it is REALLY REALLY quick. Makes most other amps seem lethargic.

Closes in on the tube sound...........but not as smooth as my Manley stuff so let's not get stupid here. Vocals, acoustic instruments all very well represented. Quick, but not rumbling full warm bass. Tight distinct bass. Good luck in your search.
It's all about synergy with your speakers. I have a creek destiny and a sim audio i5.3 and they are both great with the right speakers. The sim really works great with dynaudio but was a real bore with a set of Von schweikert monitors. The destiny sounds great with those same vs speakers but not as good as the sim on the dynaudios. I would ask the manufacturer of your speakers. Chances are they know what sounds good with them.
I am very satisfied with a BAT VK300xSE with the tubed front end. As mentioned by others synergy is most important. I have Acoustic Zen Adagios and first had a Wyred 4 Sound STI500 integrated and then an NAD M3. Both had terrific qualities and may have worked fine for another listener or speakers. You might have to try a few highly recommended and well reviewed amps before you find satisfaction. Good luck.