Sonographe was conrad-johnson's budget line. As such the trickle-down theory was in play. The parts and build quality were "good" [or better] but do not rise to the level of their higher line gear, as you would expect. But one still gets a good dose of the c-j house sound: smooth, lush, and pleasant if not totally faithful to the source. But who wants to listen to dry, sterile, lifeless tunes?
There is a reason for c-j's longevity--lots of happy owners of thoughtfully-engineered products. Service is excellent and Bill Thalmann is a great resource for repairs and mods.
I owned a Sonographe preamp and CD player [and Synthesis spkrs] and they were quite satisfying for their modest origins, and a big step up from the offshore offerings of the day. The player eventually died after a long life of good service. The amp may have life in in yet, but an audition and evaluation is ideal, if possible.