I haven't tried the KT88 but I just tried the 12AX7 and they are very good. They compete with NOS. I liked them better than my 1950's RCA black plates so they now stay in my mono blocks. They are not made by Shuguang but by an independent company. If the 12AX7 is any indication of the quality, then I cant wait to hear the KT88's though they are expensive.
