Cool video, I recognise those speakers & have been looking for a while to see them. My dad had a pair powered by the Rogers A75 Series 2 amp. He brought them as a whole new in '79. Sadly the speakers were drowned in a flood years back. But I have the amp which I seriously love. It's on my PC's audio out. (Which has a x570 MSI Gaming Plus main board.. I choose this due to audio DAC). The amp sounds great when the output is set to Ultimate power in Realtek software panel. Rare to see would be rarer still to see them on a vid together amp & speakers - Rogers MAJ5 +A75 Series 2. There was a sub bass amp and speakers also from that series/time for this setup. I think the crossover Amp was called XA75 & the subs L35b.
That audio socket is a DIN speaker jack. Very common in Europe back in the day, but now almost obsolete, I believe. They made for an easy connection, but they weren't very good electrically.
