Trelja, thanks for your kind offer. Russ is sending me six each of his spare KT-90's and MO KT-88's to try out in one monoblock against my 6550C's, and this should greatly help me get the way pointed right.
At least with the KT-90's, there's only one kind of the tube currently produced. As Jkaway notes, there are choices when it comes to 88's. I actually found that I preferred the Chinese Ruby 6SN7's over the Sovteks for the driver stage of my CJ MV-55 amp, but have never tried any Chinese power tubes, and generally haven't liked any Chinese 9-pin miniature dual triodes, so I was pleasantly surprised. I'll take a look at the website.
At least with the KT-90's, there's only one kind of the tube currently produced. As Jkaway notes, there are choices when it comes to 88's. I actually found that I preferred the Chinese Ruby 6SN7's over the Sovteks for the driver stage of my CJ MV-55 amp, but have never tried any Chinese power tubes, and generally haven't liked any Chinese 9-pin miniature dual triodes, so I was pleasantly surprised. I'll take a look at the website.