I used to own an Acoustat TNP preamp, my first high-end preamp (sister piece to the TNT amp, trans-nova technology). Is this the unit you're talking about? If so, it was very good in its time, favorably reviewed by J. Gordon Holt in the early 80s, but comparatively noisy compared to current units. The phono stage was its strength, as was the case with the best preamps in the times before line stages became the main source. In any case, you might check for extra noises, when I sold mine it needed to have a number of caps replaced.
