why do Ortofon SPU C from the 50ies sound so good?

Dear Thuchan: +++++ " Nevertheless I was wondering because most people regard that old vintage stuff not as HiFi or even High End which is not true - " +++++

that's why exist that long MM/MI thread that confirm your statement with cartridges in the 40+ years old range ( not 60 as your cartridge. )

Now, I own old Ortofon LOMC cartridges and today IMHO are competitive, I own the MC2000, MC30 and MC20MK2 and all them are better that any one could imagine.

Not only Ortofon but other vintage ( by 1980. ) cartridges are really god like Goldbug Ms. Brier or Pioneer PC-70MC or Satin M21P or Victor MCL1000.

So it is no surprise your Ortofon mono sample. As Martinhall point out several vintage cartridges sound good in those old times and with our today systems it still sounds good.
This fact IMHO is a testimony of its great design, build quality and very good execution design.

Regards and enjoy the music,
Raul.

Dear Thuchan: I never hear/heard that great EMT so I don't have an opinion if like you say is the " ultimate phonostage/preamp ", what I can say is that is the most versatile phono stage equalizer out there.

IMHO as is important and as makes a difference that very old recordings be played through a matched inverse eq. curve as important is that any cartridge ( LOMC or MM/MI ) be matched with its precise electrical needs: this makes " the difference ".

Anyway, good to hear that you are enjoying music better than ever at your place.

Regards and enjoy the music,
Raul.