@atmasphere Roger, you might want to do some reading at the links I posted in my prior post. Most of this post (except perhaps the comments about subjective listening) is incorrect. As I pointed out earlier, the load is not for the cartridge's benefit- its about the preamp.
Please explain. Im all ears.
There's plenty of old school audio electronics that used the 6SN7. As you know, its geometry is similar to that of the 6CG7/12BH7 and 12AU7 (the latter being the same as the 12BH7 but with the entire structure sawed in half)
My dad built the WM-2 in 1956 so I am very aware of 6SN7, as was Heathikit who used them everywhere they could. Are you aware that most of their early products were built largely from WWII surplus of which there was tons. They would buy tons of surpus and then figure out what to do with it. 6SN7 were in great abundance. I think a 6SL7 might have made a better choice and I snuck one in a Williamson, changed a few resistors, and really liked it . Much more linear tube (low distortion). Why, because it was made for audio, not B&W television.
There are some great books on the history of Heath written my people who were there.
This other stuff about sawing tubes in half make no sense. Ive taked to tube designers and they dont talk that way... at all.
As to it being lower in microphonics, the tone is of course different as the structure is different. But I would not say they are less microphonic than a modern 6922. But this is just my experience of testing over twenty thousand 6922s