I went ahead and spun off a batch of 5 boards through PCWay using your gerber files, built up one of the boards, and shazam! if it didn't work perfectly on the first power up. I ordered some of the higher voltage transistors just in case the 2N390x transistors proved themselves underrated, but so far have not had to use them. It appears to work quite well with the lower voltage jellybeans. It was happy to deliver a full 40v, 10KHz signal into loads as low as ~68Ω (well over 100mA) without significant distortion. Very impressive, indeed.
One trap for young players (I'm 59, but evidently somehow still a young player): Be sure to insulate the legs of the transistors that have the ferrite beads. The circuit will work great while the PCB is upright -- that is while the 3325 is upside down during installation -- but as soon as you smittenly button it all up and heft it back onto your equipment stack, and pile a few other heavy pieces of equipment on it for good measure, the ferrite beads, which are of course conductive (duh) will slide up the transistors and short one or another of the leads.
One other thing I didn't see mentioned was removing the option jumper on the A6 logic board located between the configuration switch block S1 and U43 to let the logic know you've got the 002 HV Option installed.
I do now have a three extra unpopulated PCBs that I probably will never use, if anyone's interested. PM me and I'll send you one. First come first served. Note that I did not opt for the gold plating, so they're just regular tin plated. So call me cheap. See pics.
Anyhow, a huge thanks to TERRA Operative for the Gerbers and associated files and for all the work you put into them. Thanks also to the other contributors who's comments were quite helpful.
- Scott