Look for the Rogue group on Facebook (I love my Rogue Audio Gear) - you’ll get more feedback. The Gold Lion (Russia) KT88 has been getting traction as the favored power tube in Rogue amps. It has a better midrange than Tung-Sol KT120. The KT120 is still good, to be sure. KT90 are a bit bright in these amps. Rogue gear tends to have less midrange sweetness that other brands of tube components, so the Gold Lion KT88 is a good move to help mitigate that.
Small tubes - you could go anywhere. Many vintage makes are great. New Russian options like Gold Lion, Mullard, and Tung-Sol are also great. Electro Harmonix 12AX7 / 12AU7 and 1980s Philips ECG tubes are too bright / sterile for me - not particularly recommended on either. RCA clear tops used to be the ubiquitous NOS 12AU7; they’re OK - I don’t love or hate them. Mullard anything is warm. You can also sub 12BH7 in for the 12AU7’s - it will give a more detailed, dynamic, punchy sound than 12AU7. This slot (amp driver) is about the only place you can get away with 12BH7 sub, because they’re much noisier than 12AU7 in other slots. 5814 is another 12AU7 sub you can use (much closer sub than 12BH7) - I like the GE gray-plate, triple-mica 5814.
Mark O’Brian (head guy at Rogue) recommended the Brimar and Telefunken small tubes in his amps for ages.
