Does he use with upright?
This unit has low impedance input, so maybe works with the Ehrlund pre, it has narrow band Q too.
Actually, I believe he used it primarily with a Rob Allen fretless. He did own a Czech Double Bass, but apparently he's selling it. Hard to say. Once you've inserted the Ehrlund Pre into the signal chain, the impedance matching is taken care of, at least into my amplifiers. When I've sent the EAP FOH the engineers haven't had any difficulty with EQ.
Ric