I still watch this thread. Time flies. Noticed your WTB post, hopefully you'll get a hit.
BTW I own both a nice DIY CTH and a Massdrop CTH and rotate both in from time to time. DIY CTH gets play because of its greater tube rolling (voicing) options; I've lots to choose from and find that fun. But my "budget" β22 is my mainstay.
Hope I get a hit too, but I imagine its a long shot.
If I had a clue what I was doing I'd take the schematic and do a build either point to point or with breadboard. The "compact" part really isn't a factor for me, it'll be for home desktop (bedroom) usage only.
My Vali2 is a decent enough amp, but really doesn't showcase the tubes, probably due to negative feedback. Does the CTH use negative feedback? I haven't read anything saying one way or the other.
What's this "budget" β22 you mentioned? I tried clicking the link in your sig, but it's dead.
Thanks for letting me know. Updated a few of the links in my sig.
I've built and heard a lot of headphone amps. Part of the reason I stopped building; Too much audio gear & not enough space (or ears Though I do plan to someday build out a Bruce Heran 6DJ8 Headwatt I bought the parts for years ago. Assuming I can create a work area somewhere in the condo we moved to.
Anyway, based on my ears & listening prefs I couldn't easily discern diff amongst 2-, 3- & 4-channel β22s so sold most & paired down to a bare-bones, non-traditional, cheapo 2-channel β22... Plus AMB γ2, a few sets of cans & DIY CTH & Massdrop CTH in rotation. As you may have read, tube rolling has a lot of effect in the DIY CTH design, IOW it permits tube choice to color its sound more than many other amps. Hopefully one will popup sometime for you to try. Maybe setup an alert somehow for new FS Headamp posts.