Warm sounding 6922 Type Tubes

Siemens and Halske with a External Acid Etch Serial Number, the versions with the Plate internal with a Serial Number are not of the same level of performance. 

The CCA from the 50's will also be a very close performer to the Acid Etch.

@pwerahera 

Thanks for the list. I spoke to Brent today and he suggests giving a NOS Amperex 6DJ8 a try. 

If Mullard’s aren’t doing it I doubt another tube mfg. will.  Seems like you should be looking at either the DAC (you don’t mention the name) itself or another component in your system.

Why do dacs have tubes?

@earthbound The Mullards are starting to warm up and probably didn’t give them enough time to break in. I guess there’s no set time especially for NOS tubes.
 

The real problem is I have tinnitus in my left ear and it’s extremely sensitive to high frequencies so that’s why I lean towards a warmer sound. I can no longer listen to loud music without being affected. I should have mentioned this initially.