@ghdprentice I modified the Marantz 7C a bit using recommendations for upgrading given to me in a letter by Saul Marantz himself. I only used it for 5 years as my front-line preamp until I replaced it with an Audio Research SP6B preamp in 1981. The Audio Research had a far more specific sound stage with much tighter bass, but the Marantz soundstage stretched wall-to-wall, while the SP6B only went from speaker to speaker and had this "paper ships on a paper sea" image, not as holographic as the Marantz.
Funny story: the Marantz paid for my moving from Northwestern University to the University of British Columbia (post-docs) because the moving truck had a leak and soaked the box the Marantz was in. Based on a repair estimate from an audio shop for rebuilding, they settled for $3000 and let me keep the preamp (!). The preamp worked fine after I replaced some connectors and a few capacitors. I later traded it in for a set of new speakers in 2003 (ATC's), so it was quite the investment return for $200 non-working in 1976!

