TONE MONSTER 3 Band preamp.
I don't have a bunch of experience with this thing, it came out of a custom bass project that went south (bad neck, terrible excuse for a builder who wouldn't back it up, but no issues with the preamp).
It is a functional preamp. It has a stacked pot for B/T, Mid, Pan, and Volume. No bypass, but if you wanted to wire one in, you could. There appears to be a gain adjustment as well. 9v operation.
There's a set of gold knobs that will fit it for $10 extra, if you need them. It appears to fit most standard knob sets.
Asking $35 obo shipped to the US
Paypal only
Int'l, PM me for a quote.