I have a Behringer Xenyx 802 that developed a nasty hum

If you have an unbalanced signal (only two wires), then ground hum occur and you need a ground isolator like this

Placed near a wall wart transformer you will get 60hz hum, isolate as much as possible

Believe it or not I like the Behringer anti-hum better.

This created an audible hum in the keyboard amp.

Something in the signal flow between my computer, my Firestudio Project, and my Yamaha HS50m studio monitors was causing a distracting high-pitched hum, making it difficult to do any tracking or mixing

This worked extremely well and removed all audible ground hum (especially from the

I would also assume it would destroy the hum from instrument level signals also