Well, well, well, look who it is!
Jonathan, having heard your system myself a couple of times(albeit with the Dynaco PAS4 preamp while your AI was being modded), I would like to offer up a few recommendations, if you don't mind.
As your preamplifier and loudspeakers are at a very high level, the next power amplifier you bring into the system must be on the same level in order for your system to be maximized.
I am of the opinion that system synergy is more important than individual components. That being said, I feel that goals of the new power amplfier be foremost, refinement, and secondly, ability to power the loudspeakers. I believe that an amplifier that addresses those two areas can then be analyzed to see if they can take care of everything else - ability to control the woofers' voice coils, macrodynamics, liquidity, treble extension, etc. Also, the amp should be on the more polite side of neutral as the presentation is already lively, and I don't expect the AI preamp to back off on that.
Parts quality, particularly transformers, what I always blather over with a tube amplifier, should be a particular focus.
All of my BS aside, the power amps...
My biggest issue with Conrad Johnson products is they do not attain the refinement as some other amplfiers I have encountered. That being said, my ideals regarding system synergy proves they can work very well in the right system - including yours. I have heard the CJ MV60, and it did not sound good in the sytem I listened to, which I am willing to pardon the amp for.
One amplifier I definitely suggest is the Cary V12. It has the ability to drive most loudspeakers to quite loud volumes(which you know I definitely listen at), with excellent refinement, and retrieval of detail, combined with smooth tube sound.
I am not nearly as high on the Rocket 88, as I find it overripe, sluggish, and slow. But, I will admit that when used in a certain forward system I heard one day, I found it to offer unexpectedly great sound. If your system with the AI is a bit too forward, and your budget is limited, it's an amp to at least consider.
BAT products have always really made me smile with their fabulous sound. If your budget is higher than the Cary Rocket 88, these are terrific products. Some complain that the stereo amplifiers are not up to driving some loudspeakers, but I they will put out a fair amount more power than your current amplifier. BAT amps have a warm, graceful, relaxed presentation, which offers tremendous depth and realness, but with great extension and slam when called for.
Next, the AtmaSphere M60 monoblocks, although I am uncertain as to their ability to drive your loudspeakers. To be frank, based on my experiences with my second system, there are probably not a good match from an impedance perspective. And, their larger products may not fit into the direction you may be looking toward(size/price). But, the clarity, speed, and immediacy of a good OTL amp can be startling when combined with a sympathetic load. There is a realness present which is not matched by either tube or solid state amplifiers. Downsides, in addition to demanding high impedance are a massive amount of heat, electrical consumption, and the inability to grab hold of a woofer's voice coil and wrestle it to the ground(may be a prime concern in your case). Of course, you are welcome to borrow my AtmaSpheres for an afternoon or a week to see how things work.
Oh, and please do not ever forget about Air Tight and Granite. GREAT tube amps. Heard both, love both, would not mind owning either, but there's only so much you can buy.
One additional brand which I have not heard yet, but will on Sunday is Wolcott. I have heard from several people I put a lot of trust in that they are simply splendid. I am looking forward to Sunday to find out for myself.
Finally, a brand that is no longer well represented here in the USA, and can sometimes be unlucky in terms of reliability(knock on wood in my case), Jadis. Jadis is simply as good as tube sound gets. I don't often recommend them these days for the reasons I outlined above, but if someone is looking for a tube amplifier, if their system is up to it, and they know everything going into it, Jadis is perhaps the gold standard of push pull tube amplification.
GOOD LUCK,
Joe
