I agree with other respondants who opine that the GFP-750 is an exceptional value when purchased used. I recently replaced my GFP-750 with the new "Gain Cell" preamp from PS Audio. The new preamp is still breaking in, so I reserve final judgement, but I can confidently state that it is more resolving than the GFP-750. First impressions include a lower noise floor and higher resolution of detail, as well as greater dynamic contrast and speed, the latter particularly noticable in the bass region.
The only amplifier that I have paired with either preamp is the PS Audio HCA-2. The GFP-750 works very well with the HCA-2 in passive mode, using either single ended or balanced interconnects. Resolution is exceptional and dynamics are surprisingly good. Avoid SE cables, however, if you intend to use the GFP-750 in active mode with a very transparent amp like the HCA-2. With SE cables in active mode I consistently found the sound to be veiled, and fatiguing with extended listening, in comparison to the passive mode. Upgrade to a good set of balanced cables, however, and the active mode sounds just as transparent and sweet as the passive mode, with a touch more heft in the bass region. I enthusiastically recommend Synergistic Research Kalaidoscope Phase II cables (balanced) as an excellent choice for anyone interested in pairing the Adcom GFP-750 preamp with a PS Audio HCA-2 amplifier.
The only amplifier that I have paired with either preamp is the PS Audio HCA-2. The GFP-750 works very well with the HCA-2 in passive mode, using either single ended or balanced interconnects. Resolution is exceptional and dynamics are surprisingly good. Avoid SE cables, however, if you intend to use the GFP-750 in active mode with a very transparent amp like the HCA-2. With SE cables in active mode I consistently found the sound to be veiled, and fatiguing with extended listening, in comparison to the passive mode. Upgrade to a good set of balanced cables, however, and the active mode sounds just as transparent and sweet as the passive mode, with a touch more heft in the bass region. I enthusiastically recommend Synergistic Research Kalaidoscope Phase II cables (balanced) as an excellent choice for anyone interested in pairing the Adcom GFP-750 preamp with a PS Audio HCA-2 amplifier.