In a jazz cafe, I assume the music plays low most of the time and so it probably doesn't matter much.
"Now that I think about it, there was nothing in this shop that would tell you it isn’t still, say, 1960."
I'd go for 1980s based on the amplifier, turntable and speakers. It would be a radiogram, probably valve based, in actual 1960s. Nice though.
But besides that, those speakers are placed terribly for stereo imaging. Even tucked in the cubby, why place them with the drivers together rather than apart? And those speakers appear to be dreadful anyway. A single 12" driver in a vented / untuned baffle with no midrange or tweeter elements?
So this is definitely set up for aesthetic, not sound quality.
https://news.ycombinator.com/item?id=44358442
(There could be another amplifier somewhere out of view.)
If you sum the stereo channels into mono then feeback present but inverted on each channel is cancelled out and the problem goes away like magic.
This seems to be lost knowledge but it's how old school sound systems[1] were able to have their turntables basically on top of a collection of speakers without feedback.
Many mixers back in the day, from people like Pioneer, used to have a mono/stereo switch for this purpose.
It's very easy to demonstrate this by placing a stylus on a stopped record, then tapping the record surface directly
The speakers are right next to each other so it's not like you're loosing stereo image.
1. I'm talking old school Jamaican and UK Sound Systems here. https://en.wikipedia.org/wiki/Sound_system_(Jamaican)