It's unfortunate that you are having this issue with your Slingbox after upgrading your set top box. There are a few things that you can try to either resolve the issue or locate the source of the problem.
You can switch out the audio cables with a new set. You can connect the Genie directly to the TV to see if the humming is present on the TV set. If you could, you can connect, say a DVD player, to the Slingbox to see if the humming is present on the Slingbox, with another audio/video device connected to the Slingbox.
Please follow the steps provided and let us know what occurs.
Awaiting your reply,
Sling Media Moderation Team
I am just now connecting to my sling box via desktop. I just upgraded to Genie, and now hear a tone in the background all the time. This did not happen with my older HR21 DVR, and I'm connected the exact same way.
Is there something I can do to get that tone to go away?