Shure e.530s.  I've never had anything plugged into the input.  Its always just been used as a dac/amp from my laptop and/or desktop.  I should try that sometime, I didnt think of that.  Cables = whatever USB cable I have lying around for the desktop, or the short USB cable that I requested with the Pico.  And the headphones.  And in this case, the Pico is the source, since I have the dac/amp model.