Went over pretty well, I'm really glad I made them. The booth behind mine was an amplifier company (super nice dudes, but absurdly loud), and with the headphone amps and some nice Audio Technica phones people were still able to get a good idea of the pedals' sounds.
Also, there were a number of people that came to ask about the headphone amps and didn't care about the pedals, as well as a number that tried the headphone amps and loved the sound, so now I'm considering updating the design with some useful features that would make it a releasable product. Ian Martin Allison came over and commented that he would love something like that as a practice tool, partially because he liked the aesthetic of it.
So short answer, they worked out well.
Long answer, I'm now thinking of adding:
- aux in for practicing with a track
- XLR out
- dummy load (so it can be a standalone D.I.)
- switchable stereo or bridged mono input (currently only works as bridged mono)
Also considering a different enclosure so I could fit the tubes and transformers inside the chassis for a sleeker look.
The headphone amp is not at the top of my priority list, but it's made its way to the list of things to poke at more.