It’s complete bullshit cuz that field doesn’t interact with the already shielded signal cables. You can also have the speaker cables shielded if you think that field with interfere with a signal that large.

In any case, even if it does interfere, you can’t hear the interference, I guarantee you that. No human can, and this has been proven on multiple blind listening tests, yet these things still sell 🤷. Sheep will be sheep.