Benson Preamp

This one just traced over on FSB. It's essentially a modified Wampler Plexidrive with an added bass control. Unless you're really sure any through-hole J201s you have on hand are in spec/authentic, I'd suggest using MMBFJ201s, which are the SMD version which are still in production and much easier to get in spec than the discontinued through-hole version. SMD to through-hole conversion boards here.

Update August 19, 2019:

Corrected a few values that have now been confirmed by Benson. The traces haven't changed however.