I bought a CAT SL-1 III used, and sent it back to the factory for a phono stage. It had two NOS tubes replacing 6922's, and the factory told me that was a bad idea, that they weren't rated to handle the current the 6922's in that position would get. So I'd check with the factory on where it's SAFE to use other than 6922's. They're very friendly and helpful. Phone number: (716) 359-2700.
