I've seen a few posts in the requests over the years for people looking for a preamp for Piezo pickups. The Barcus Berry 3000A is designed to work for acoustic piezo pickups but is also a buffer, preamp, and EQ. This is the only info that I could find on it:
The Barcus Berry 3000AE Piezo Buffer Preamp with EQ is specifically designed to work with all Barcus-Berry electret microphone systems. Features external bass, treble and volume frequency controls to allow a wide range of adjustment. Includes a belt clip for unrestricted movement.
Barcus Berry 3000AE Piezo Buffer Preamp Features:
• Designed to work with all Barcus-Berry electret condenser mic systems.
• Features external bass, treble and volume frequency controls for a wide range of adjustment.
Barcus Berry 3000A Product Specifications:
Input (EQ) Flat
Input Interface: RCA unbalanced
Input Impedance: 2.2 Meg Ohms
Maximum Input Level: 2.0 vrms
Output (EQ Flat, Volume Max)
Interface: 1/4" unbalanced
Impedance: 2K Ohms
THD: .008% @ 1kHz
Bass: +/- 12dB @ 50Hz
Treble: +/- 12dB @ 10kHz
Frequency Response: 5 Hz - 30kHz (+/- 1 dB) Power Supply
From what I see from the schematic I have no question that it will work with any Piezo pickup, as there doesn't seem to be anything really special to tell me it can only work with theirs. Mostly it's just marketing to get you to buy their pickup.