Headphones with USB

  • I have a pair of headphones I can use in the meantime until I decide on better studio headphones, but I have to use the USB attachment for enough length. I tried this in the kemper and i didnt get any sound. Is there something I missed or Kemper won't accept headphones with USB plug. I do have a 1/4" adapter, maybe I can just use that and go into a monitor slot?