The length of the cable is less likely to be an issue than a ground loop-like hum.

Since you are talking about 40' away, it is likely that you will be powering the amps from a different household power circuit than the processor.

To the extent that the different circuits have different loads on them, you may encounter 60 Hz hum at your distant speakers.

You may be able to fix the hum with special ground loop isolation cables, but they are not cheap and not 100% transparent either.


You should check to see if both ends are powered by the same circuit breaker in the home panel. If they are controlled by the same breaker, you will probably not have this issue. If they are different, you might want to look into expanding your rack as a cheaper and more accurate solution.