I just switched from a Beosystem 3 to an Anthem MRX 1120. I have Beolab 18, 7.1, 2 and 3 speakers and Cat 7 house wiring. I built a converter using a shielded RJ45 patch panel. It takes RCA line level audio from the preamp and converts to Powerlink RJ45. I pull a trigger for each speaker out to a Raspberry Pi4 so that I can switch them on/off using GPIO. The RPi is using an B&O IR eye to control it (see /forum/imported-unmapped/using-a-raspberry-pi-as-a-diy-equivalent-to-logitech-harmony#post-2168670).
It took a lot of work to get the grounding right but it's 100% hum free and doesn't pick up dimmer noise. Line level audio is very picky so shout out to Steve from Sounds Heavenly for making quality options available with his excellent cables for those who don't go the DIY route.
Photos attached, hope they are useful.
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