I would agree with Bill; they're basically just bar magnet single-coil pickups, but wound with a lower impedance. I've tried plugging them into an amp completely direct - no electronics whatsoever. They sounded fine. The only significant differences between them and any "typical" single-coil pickup were:
- They sound a BIT different from standard pickups, most likely because the low-impedance design is meant to make their frequency response very flat, as opposed to the more "typical" frequency response curve of standard single-coil and humbucker pickups. Without the Series electronics, they sound more or less like you have the Q switch off, and the filter knob all the way open.
You could then easily replicate the basic effect of Series electronics through other means - e.g. a resonant low-pass filter pedal (probably best), a graphic EQ, or maybe even a stationary wah pedal. Wouldn't sound QUITE the same, but generally similar.
- Slightly low output, although not as low as one might think. Hence why putting some kind of onboard boost like a Blaster might be a good idea.
- MAYBE more susceptible to noise/hum than a typical single-coil? But I'm really not sure on this one - I don't recall hearing drastically more noise when I tried it.
It would actually be pretty interesting to hear what a set of Series pickups sounds like in, say, any garden-variety Strat body, provided they're mounted in the same relative positions along the string length as a Series guitar. Then maybe include an onboard Blaster for buffering, and run it right into a resonant 2-pole LPF pedal like the Behringer BM-11M. I've thought about doing something like this before; it'd be really interesting how close you could get sound-wise.
Or keep them as spares! Nice to have those extras just in case.