The GG has a DC filament with a voltage regulator. I eliminated the voltage regulator and used Schottkey diodes and a couple of resistors like snubbers to reduce voltage for the filaments.
I used UF4007 diodes with snubbers for the main supply.
The input specs a 10K grid stop resistor. I used a 68K tantalum resistor with an Alps pot in shunt. Used tantalum resistor for other resistor in signal circuit.
I tried Auricaps 3.3mfd output caps. It could possibly shatter glass with the Auricaps so I used Jensen copper foil PIO caps to tame it some.
I don't know about the extra output but I would imagine it is possible. I have only one in and one out. There is an on off switch and the volume control, that all.
Look here:
http://www.users.qwest.net/~pspwr/foreplay_multiple_outs.html