6922 family (CV2492, CCa especially) are dramatic improvements over the various 5670 native equivalents, even better than the excellent 2C51 and 6cc42. I have not been convinced regarding running 6sn7 in mhdt DACs. While many aspects of sound are better than from the native 5670 variants, I haven't found 6sn7 family tubes to be as uniformly advancing and transformational as upper tier 6922 variants.
This includes trying Treasure CV181z, 1944 production Sylvania 6sn7a metal base, Syl bad boys and fat boys, RCA coin base, various Tung Sol and Ken-Rad off-letter variants. 6sn7 can beat basic 6dj8 in the MHDT upgrade buffer sweepstakes, but once you get into the upper tier of 6922 alt-tubes, my experience so far is that there's more nuance, tone and precision in the premium 6922 path.
Phil
This includes trying Treasure CV181z, 1944 production Sylvania 6sn7a metal base, Syl bad boys and fat boys, RCA coin base, various Tung Sol and Ken-Rad off-letter variants. 6sn7 can beat basic 6dj8 in the MHDT upgrade buffer sweepstakes, but once you get into the upper tier of 6922 alt-tubes, my experience so far is that there's more nuance, tone and precision in the premium 6922 path.
Phil