Major;
The excellent description above by Tournedos could not have been better stated.
On the subject of transformers, I use one per B&0 device, on the premise that if a device or transformer goes down, the remaining do not suffer the same fate. By the way these are BL 4000 speakers, and not an easy conversion like a simple jumper relocation in a Beosound 1.
Everything ultimately should be run through a good surge protector, before connected to the wall mains socket. If the electrical power goes out, and then comes back up slowly, it does the most damage to computers, printers, and B&O.
It sounds like your new apartment has moden wiring which is a plus. Nonetheless, it is a good idea to verify what the apartment maximum service load or service is.
Yes, Japan was certainly different in 1968. The most expensive item I saw in Tokyo then was a large apple strudel. ( Couldn't afford it as a poor student, so I finally learned how to make them ).