I own, so can highly recommend Cayin Equipment quality and tube sound. Designed in Germany, made in China, a brick s...house. I took the bottom off when I got it, very impressive inside.
I bought a used A88T, It lets you run 6550’s or KT88’s, which is nice, it came with 6550’s, very nice, tried and prefer KT88’s, just slightly different. Optional Pre-Amp Pass Thru for future changes to your system
this review helped me decide.
https://6moons.com/audioreviews/cayin/a88t.html VAS, USA Distributor, is highly respected.
Consider remote control features when you look (they are not always mentioned, you may need to dig for answers).
A88T has a remote, input switching (who cares?), volume remote which I must have, and remote triode/ultra linear switch, easy to hear instant difference while listening (I and everyone of my friends definitely prefer ultra-linear).
No remote balance, which is a must for me to tweak the imaging a bit on ’a bit off’ tracks. I get that via Chase RLC-1
Also, any modern tube amp, check for external bias control, and bias meters, I wish I had that. My early version lacks that, but it had 16 ohm speaker taps which I need.