Tube overdrive using NOS 6111 subminiature tubes.
Likely a one-off project.
I had room left on a PCB order and had a tube lying around and was curious as to whether it was possible or not.
It is, but is rough and loses a lot of output.
Consumes about 400mA from +12V. The tube and the filament regulator get very hot in operation.
http://syinsi.com/shop/tiles/tube-overdrive-tile-pcbpanel/
Module is available as a DIY project only.
No info about availability.
Module is a 1U tile