My dear friend
@damacman will say MC7270 or (possibly MC7300) but my vote would go to the MC2205 which is the (period correct) ideal compliment to the C32. Second to that, I would go with MC2255 which is slightly more refined but still a good match to the C32.
Recently a new ribbon cable kit has been manufactured for the C32 and I believe it has received McIntosh's stamp of approval, so the issue is relative. Installing it however is not a job for the amateur unfortunately but once done, it should never be an issue again.
The C32 was a significant new product at the time of its introduction in 1977 and is still a highly regarded preamplifier.
Congratulations and enjoy.