Warm sounding 6922 Type Tubes

Are the Mullards fully broken in? Tubes can be quite harsh sometimes in the beginning. 

I prefer using the clearest and most transparent tubes rather than dulling things down due to harsh sources. Fix the DAC. Cca run about $400 a pair.

I've never heard of a 6922 that folks called warm. Their claim to fame is clarity and details iirc. There are adapters to allow for the use of different tube types, maybe that'll be an answer for you 

@gregdude has an idea. There is a tube seller named Tubemonger. They sell socket savers and adapters. One of the adapters allows you to plug a 12XX7 tube into a 6922 socket. Here’s the link:

Tubemonger tube adapter

Before you try a tube adapter, I’d talk to someone knowledgeable about your DAC and Brent Jessee as well as the people at Tubemonger to make sure it’s a good idea for your DAC.

The link says it adapts to an ECC88, which is what the Europeans call a 6DJ8.

The following information was taken from Joe's Tube Lore posted back in 1999. I have some of these tubes and confirm his descriptions are fairly accurate. Only issue is tracking down these as they are hard to find and could be pricey.

Siemens 6922 / E88CC (with shield, gold pins) Now things are getting more interesting. It’s lively, has a palpable & real quality to individual performers with greater dimensionality than any of the above tubes. Warm, lively & transparent with an extended high end. This is a classic tube and an excellent choice in this family if your system is not already over the top in the high frequencies. Often found labeled as a made in West Germany RCA for as little as $20 a pop. An absolute bargain....

Siemens 6922 / E88CC, RCA label (A frame, gold pins) This tube is similar to the earlier 6922 above. Vocals are slightly bigger and slightly more forward, the highs are a bit softer and the overall sound of the tube is a bit warmer. Music is presented with a warm, vibrant acoustic. Very nice & musical, though it might be a bit dull in a system that’s already dark in balance. Another excellent tube..

Siemens 6DJ8 / ECC88, RCA label (with shield, steel pins) Kind of lives in between the two 6922s above. Warm & vibrant, with a slightly forward balance similar to the A frame. Slightly more extended highs than that tube, however. Another very nice tube, frequently found labeled as a made in West Germany RCA

Siemens 7308 / E188CC, RCA label (with shield, gold pins) - Sacrilegious comment time. I prefer the slightly warmer, more vibrant and wetter sound of this tube to the sound of the CCa. Closest sound among the Siemens line to the sound of my favorite Amperexes

Amperex 6DJ8, Orange globe logo, Holland (shield, steel pins,) Much better than the above tube No comparison in fact. Warm, vibrant, lively, grainless, transparent Amperex sound. Killer tube. Almost as good as my reference Amperex 6922s (coming up soon). I slightly prefer this tube to the best of the Siemens 6DJ8s, 6922s & 7308s.

Amperex 6922, PQ, white label, US (shield, gold pins) Another very good Amperex tube. Warm yet lively, focused, grainless and transparent. A winner one of the best. Dynamic with punchy bass to boot.

Amperex 6922, USN, white label, US (shield, gold pins) Sounds very much like the US white label PQ. Another excellent tube though it may lack just a bit of that tubes warmth & body, but I’m quibbling here....