Anthony Gallo Ref 3 - Bass Solutions with Tube Amp

Jackd, certainly it would--I guess 'most any stereo amp would work--but you still need a low-pass filter including gain controls. How 'bout an old Dalquist DQ-LP1? It had variable lo-pass filter points, gain controls, and a bass-boost control. Lo-pass slope is 'only' 12dB/octave, but that may be plenty fast enough.
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Just had a thought...maybe the 'fuzziness' or 'lumpiness' (or whatever TAS's reviewer called it) in the Ref. III's sound with the bass amp used is caused by the inherent phase errors of its low-pass filters.

Another thought...depending on its bass-equalization capability, Gallo's bass amp may be quite reasonably priced.

These speakers certainly fascinate me in spite of my loving my current quad of very efficient Kindel PLS-As.
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Rich, looking forward to your findings with the parts express amps.

Curtis