I am experiencing a hum (it is one consistent tone, and appears just before sound happens in a recording, and continues for several seconds after sound stops) in my Velodyne DEQ-10R subwoofer whenever I play music from my laptop. I connect my laptop to my Tivoli Model Two from the laptop’s headphone/speaker output to the Tivoli’s “Mix In” input. The cable I use is a Staples “Mini-Stereo Audio Cable” (it’s a 3.5 mm (1/8”) male TRS/jack plug, identical on both ends). I have tried moving my computer away from the sub, but this is clearly not a magnetics issue and it is only present when the cable is connected to the Tivoli. It should be noted that even when the cable is not connected to my laptop, the hum is still present in the sub. The laptop is not the issue, it's the cable itself.
Do you think there are any cables that fit the specifications of this Staples cable but that would remove the hum? Alternatively, are there any accessories that I could run between the laptop and Tivoli, or amplifier and sub in order to remove this hum?