My Athena hiss with every source I've plugged them into. It's minimal with Mojo and the Lotoo PAW 5000 on low gain, but if I flick the gain switch it's too much.
A strange thing I've noticed is that they're very adept at picking up noise between Mojo and my smartphone when I'm streaming music. I don't notice this with my other IEMs.
They still sound terrific though.
I occasionally get some interference/noise between both my IEMs and my Cowon Plenue 1 DAP, usually when my phone is nearby. At first I thought it was my Legend Omegas but it happens with the Noble K10Us I just got in this week. Happens with both the Linum Estron BaX and BTG Starlight, so it doesn't seem to be the cable either. At this point it happens rarely enough that I chalk it up to my DAP or the fact that I'm a human antenna.