Like tornados to trailer parks, cleaning personnel are inexorably attracted to audio rooms in spite of all bans to the contrary. They just insist on it, maybe out of curiosity. I haven't had one bag a needle yet. but they have knocked over some stuff after I told them to stay out of that room.
I added a pair of chokes in the same core material to my linear PSU for my audio server project and am amazed what they do for sound. Was using Lundahls, but this is WAY better, I expect the 400H chokes have a lot to do with how the amps sound!