Thought it might be good to pull the 5751 posts over to the Quicksilver thread!
I’ve gotten a little bit more listening time with the 5751s in my setup as well, and yeah, the Eikon is the only headphone so far that’s had that kind of night-and-day improvement (though these tubes really do sound fantastic with the Eikon).
I suspected that Focal headphones would see similar gains, but the only Focal I still have on hand is an Elex. And yeah, the Elex sounds good, but not amazing, though I’m guessing it’s being limited by the scaling ability of the headphone itself.
I expected Diana V2 would be noticeably worse, but in practice, it could kind of go either way? Diana V2 sounds a little less full and less thick on the 5751s, but honestly, it’s not a huge difference, and I could even imagine someone preferring it.