It doesn’t go in your audio rack for obvious reasons. It goes in your remote power rack or better still, a dedicated machine room. Also consider (seeing as you’re building a clean install) putting in a clean feed mains supply in directly from the consumer unit with nothing else on it. As domestic appliances get on in age, Stats in Freezers, Fridges, Immersion Heaters, Washing Machines, Tumble Dryers, Dishwashers and timer switches can make a noisey spark/arc as the contacts get dirty and worn over time. Mains spikes is another consideration that in some cases can cause permanent damage to sensitive computer power supplies.
The only audio component in your setup to earth directly to the mains, is the Soundcraft mixer. Lift all other earth plug top connections. They will find their ground through the mixer and eliminate earth hums and loops.