Original Sprout hissing issue with headphone output

Hi all, I’m hoping you can give a noob some advice. So, I had the Sprout for years now, but mostly used it with bookshelf speakers and low quality headphones. Switching now to some Bose headphones, I noticed that my Sprout is making a constant hissing sound and is picking up walkie talkies or radio signal around my building. It does this with or without any inputs connected, and I tried it with a few headphones. Any advice on how to deal with it?

Welcome, slavaco88!

Though the unit could have more shielding, the chassis is relatively good at keeping this kind of noise out. Have you tried different power cables with more shielding to see if that helps?