Good 6550/KT88 tubes

you can change the sound quality by replacing the 12AX7 input tube. I used Mullard CV4004 in my 120s and the sound was warmer and fuller in the midrange though a little less extended.

hope this helps

Phil

The Svetlana KT88s will give you a more classic tube warm, smooth, liquid sound than the 6550s.

The three KT-88 choices are -- Svetlana, Tesla, and Electroharmonix. Svetlana is warm, full and nice. Tesla is also nice, a little brighter on top, little less warm. The Electroharmonix is too new and not much is written about their sound except a few people's comments how they like them. I have some for sale I bought and didn't use cause I switched to a non-KT-88 amp. The EH is being used as stock in the Magnum version of your Rogue 120, however.