You don't often see many basses with three pups. I'm planning a custom bass with an odd mishmash of pickups (a 76 Gibson T-bird for the mid position and a ZBS 440 for the bridge), and it was gonna be a two-pup bass but I have this Gibson EB4 pup lying here and I thought hmmm, that would be kinda fun to put in the neck position for when I want a deep dark retro sound. But I can't think of a good way to wire it up. I have a U-Retro preamp I was going to use, but it's only designed for 2 pickups. Easiest would probably be to rig up a 3-way selector switch before the preamp, so that I'm feeding in either the T-bird or the EB4 or both to one input on the preamp, and the preamp's blend control mixes that with the bridge pup? Or maybe I could ditch the U-retro and go passive with 3 volume controls? Or go passive with a strat-style switch? Balancing the pups seems likely to be problematic, since impedance and output varies wildly. Would something like Bartolini's buffer circuit help? e.g. the AGDB at http://www.bartolini.net/information/electronics/electronics_a.htm Any other ideas?