It's not the quietest when you have very sensitive IEMs. Not bad but definitely audible hiss when not playing music.
I get some hiss when using my DUNU DN-1000s. I thought it was my tinnitus but it's actually a low hiss. It's not really bothersome because I can't hear it when the music is playing. I got the same hiss when using it with my old X3 so I wondered if it was the player or the IEMs.