MacBook used in a Digital system

[Stratmangler]

I think that things like mains filters are ferrite beads are somewhat effective at stopping noise from the mains getting into your equipment, but are can be much more effective if you use them to stop noise generated by equipment getting onto the mains. This is why instead of using a large mains filter block I use single filters primarily on anything with a switchmode supply including the wifi router, which is close to the HIFI. Ferrite beads are on the fridge and CH boiler mains cables instead on the HIFI mains leads.

That's what I did too.
Ferrite clamps on everything but the audio system. The audio system doesn't need filtering because all the PSUs are linear, and don't exhibit the high frequency switching noise.