It was a really wierd board, custom fit to mate up with the existing pads on the Trumpet amplifier board. Ran from +/-280V supplies. Not useful anywhere else.
I did start a project called the PICCOLO about two years ago. That was to be a generic JFET headamp kit. Would have used the same differential JFET pair but with either batteries or a 6.3V heater feed from the Cornet2 (was thinking of running power wire through center hole of GND jack on Cornet2). Project stalled and I never got back to it. There's a lot of kits people ask for that I just can't get to (this, turntable motor controller, headphone amp, SET, etc.). I'll keep it on the back burner, as I think plenty of people could use one.
jh