Well, the ALO-780 have about 97 hours on them now, and continue to impress me.
While I had switched back to the RCA grey glass VT-231 tube the other day, I went back to the Hytron and found that if the tube hasn't been running for a couple of hours, I don't like it as much. I have a Sylvania "bad boy" around here somewhere, but I seem to have misplaced it when I took it out for a hum that didn't burn-off. So, today I tried two or three other preamp tubes and found the Sylvania VT-231 to be a better match for these ALO-780 ($60 tube).
I can't try this tube with the stock HFI-780 because I don't have them right now. I was impressed enough with the mods that I sent my own off today to get the re-cable done. I was planning to get these to 150 hours of burn-in for my impressions for Ken, and than I will hand deliver these to another lucky ALO customer (here in town) in the next day or two, or three...
Listening to some Jazz tonight I put an effort into over-focusing on micro details - I can clearly hear the individual snare drum brush strokes, while with my HD600 and stock cable they sounded more like white noise or hissing (I loaned out my APS cable for a few days). That same bit of detail is missing from my APS v2 re-cabled Denon D2000, turning the brush on snare into an indistinct swooshing sound.
I believe the soundstage has deepened a bit, but I don't know if that is the tube change, or the headphones, either way I like it better. Jazz at the Pawnshop is clearly more deep, not just wide.
That's all for now - I'll report back after another 24 hours.