I'm at my wits end and need help. i have a pair of Wharfdale active/powered monitor speakers. I use these in my home DJ set up and have recently only been using one speaker to monitor due to lack of space. I now have more space so put the 2nd speaker back on but the second i wire in both speakers i get a horrible, loud hum. It doesn't matter what audio device i connect them to the same thing happens.
Both speakers work fine individually but the second they're on the same device....hummmmmmmm
If the speakers get their AC power from different circuit breakers, you could have a ground loop.
Swap the speakers' interconnects channel for channel at the speaker/internal amplifier input and then at the board(?) output, right speaker becomes left and left speaker becomes right.