FWIW, during the early to mid-1990s I owned several of the classic Marantz tube components, including a 7 (aka 7C), as well as a pair of Model 1 mono preamps, a pair of Model 2 monoblock amps, a pair of Model 9 monoblock amps, and two different 10B tuners.
After performing some routine minor maintenance on each, such as spraying contact cleaner into the controls, testing tubes and replacing them as necessary, and powering them up for the first time very slowly (i.e., over the course of several hours or more) using a variable AC power supply, all of them worked fine and sounded great, with one exception. That being one of the 10Bs, which if I recall correctly had an intermittent problem affecting channel separation, possibly due to a problem with one of its opto-couplers.
The 7 was especially good sounding, as I recall, and it was a close call as to whether I preferred its sonics to those of the Mark Levinson ML-1 I also had at the time, and used for many years afterward.
My sonic favorite among all of these models were the Model 2 mono amps, used in triode mode. The 18 or 20 watts or so which they could provide in that mode were not enough for my purposes, though, with the 90 db speakers I had at the time and when playing classical symphonic recordings having particularly wide dynamic range. So I eventually sold them, although I felt a sense of loss for a long time afterward.
Regards,
-- Al