I highly recommend the VAC 80/80. Excellent value for the money. Expect to pay less than $2k used. As always, look for at least 8/10.
Try the Cayin 100. I have the 100 and 88. The extra power in the 100 may be all you need. Cayin is easy to buy and easy to sell. I've listened to the Mac, Bat and VAC, but not in my rig. It is hard to tell 'better' unless you put each amp in your rig. So, hold on to the 88, it maybe enough to provide the best sound, in your rig.
Dodd 120wpc MK II mono blocks. Any music, anytime. Find some with the cap upgrades and your rig will definitely get a big shot in the arm. between $2K & $3K when available, and depending on the tube compliment.
Great amps. Sweet! Flexible and cheap to retube.
Still more power desired? Try a Butler TDB2250, $3K brand new.
Why don't you take a few moments to tell us how your set up with the Cayin sounds now and what improvements you would like to see by introducing a different amp. Perhaps all you really need is not so much a different amp but different tubes to accomplish what you are after. Guys with SS amps buy different amps - guys with tubed amps buy tubes! :-)
Well, it isn't that I don't like the amp, but would like perhaps a bit more transparency, bit deeper soundstage, more of an in-the-room feel, deeper, tighter bass, better frequency extension, and a bit more power for complex passages would be nice. I figure that a better amp could do all of these just as well: I am sure that the Cayin, as nice as it is, probably isn't as good as some of the ones listed above. But, not really having had such an amp in my system, I can't say for sure. I am not experienced enough to say what sound I am shooting for; I just want it to sound like a live show, as difficult as that is.
Stock KT88's and upgraded Electro-harmonix rectifier tubes are what I am using now. Do you feel that tubes could get me part way there?