Hey ramble on. It could also be said that the parts such as oil filled caps all tube recording equip and mono had a role.
The RIAA curve was different as well back in the day. I have yet to hear a phonostage stage with adj. RIAA curves for the older 33 1/3 [ 10"] and 78 records. From what I'm told proper RIAA and a true mono switch is the Cat's meow.
A mono cart. alone which I did hear was a really nice improvement for mono recordings.
charles
SMA