Cheers and happy New Year!
Dryjoy wrote:I finally seem to have solved this issue - I hope I'm not speaking too soon, but it's passing all of the tests that previously would be guaranteed to reproduce the issue.
It seems that the hard drive enclosure I chose to go with the Mac Mini doesn't deal well with audio work. I'm not sure how I missed this before, as I thought I had tried running some projects from the internal SSD, however I spoke to an Apple 'genius' on the phone, who urged me to investigate the hard drive situation more.
My lovely wife has gifted me with another USB 3 enclosure for my audio drive (there have been so many financial indulgences this year - e.g. Hammond and Leslie, Mac Mini etc - that even a £20 enclosure could only be justified as a gift), and everything seems fine now. The previous one still has another three HDs in it for storage, time machine etc. Every now and again it does this sort of 'burp' where the lights go off and the fan powers down momentarily, almost as though unmounting the drives (though they don't unmount), and it seems that these burps coincided with the overloads on core 1. Somehow I'd missed this phenomenon.
It's a real relief to have finally got to the bottom of this (7 months after purchasing the Mac) and I am at last starting to bond with this Mac Mini. I so wanted to love it, but I couldn't. I've still not quite got used to the large number of cables and adapters hanging off it everywhere (I was used to my Mac Pro tower), but it seems to be a very capable machine.
Thanks to everyone who has contributed to this thread. I hope it can help someone else in future.