Thanks. You were right about the ferrite core cable clips not making a difference.

I've moved the DAC USB cable to a different input, the power cable to a different outlet than the drive caddies. I've even moved the iTunes folder to a USB-C input on the iMac.

Later (it's too early here right now, she is sleeping) I'll try to replicate the conditions and see what happens.


iMac (19,1, 3.1 GHz i5, 12.7.4, 40 Gb RAM); MacBook Air (1.8 Ghz, 8 Gb RAM, 10.14.6, 256 Gb SSD) Vodafone router and Devolo Wi-Fi Extender, Canon TS8351 printer/scanner.