We have a power adapter with these specs.
INPUT: I/P AC 100-240 V ~ 50-60Hz 1.5A
OUTPUT: O/P DC 15V == 4A A.V.
Power supply for our piano.
It hums when the piano is off and mostly goes away when the power is on.
When the piano is on, we hear humming in both the speakers and headphones.
(1) Could that be the power supply?
(2) Will a power supply filter work? If so, what do you recommend?
(3) Are there any brands of power supplies that really remove the noise better than others? If so, can you list them?
Thank you for your time.