The very alive front row center sounding Cayin A-88T is still one of the very best tube amps out there! The Cayin A-88T with its 45 tube watts and the less powerful Almarro 318B SET tube amp with its 18 tube watts, bettered over a dozen top flight amps (VTL, Cary, Musical Fidelity, Unison Unico, Prima Luna (a relative), etc) that I owned for my preference in sound in my system. (as you may know, it seems that you can often get effectively twice as much power out of a tube watt than you do out of a solid state watt)
Better late than never for a review of tube rolling. The following combination was found after an A-B shootout and careful listening with all popular tube combinations that I could find in my system:
In the Cayin A-88T, for power tubes I preferred the SED Winged C KT88 tubes (sadly no longer in production as Svetlana got bought out (kept the name) and the St. Petersberg SED factory closed) are now relatively costly unless you get the less popular SED Winged C 6550 which are slighter warmer and softer, although not bad, not the same). However, I found some Svetlana KT88 which had the same plate structure and coke bottle appearance to the glass as the winged C SED (not straight, with three holes in the center of the plate) to sound close to the SED Winged C KT88 and recommend them over the Winged C 6550, unless you want the slightly softer and warmer less dynamic sound that the 6550 produce. I found the Gold Lion tubes as well as E.H. a little too sterile, overly detailed and lean to me.
For the pre-section tubes, I found that the best combination was two RCA VT231/6SN7 made for military tubes and two military Sylvania VT229/6SL7. Or for more detail, I replaced the Sylvania VT229/6SL7 with 1940's to 50's Mullard ECC35/CV569/6SL7. The constant winner for best amp sound on balance resulted in the 6SN7 tube slot always occupied by the military RCA VT231/6SN7 regardless. I found in general that the military versions labelled VT229 and VT231 sounded the best over civilian versions without the VT prefix (with the possible exception of some 1940's tubes).
Note: if you want to go for the ultimate lush midrange, and forgo some treble and dynamics, a combination of Sylvania VT231 and Sylvania VT229 seemed to do the trick, although for balanced sound, was not optimal to me.
