Jojo,
I'm glad to hear that you are happy with your AH preamp. I'm not familiar with these Sovtek tubes. Are they a 6922 derivative? Did you get the AH preamp with the stock EH tubes? If so, then I'm surprised that you didn't like them better than the Sovteks. If you ever get a pair of NOS Siemens CCa for locations 1 and 3, you won't believe the musical difference.
I'm glad to hear that you are happy with your AH preamp. I'm not familiar with these Sovtek tubes. Are they a 6922 derivative? Did you get the AH preamp with the stock EH tubes? If so, then I'm surprised that you didn't like them better than the Sovteks. If you ever get a pair of NOS Siemens CCa for locations 1 and 3, you won't believe the musical difference.