I'm perceiving a hiss with two of my IEM's when paired with the Zen DAC on balanced. It's kind of like a background static noise. After a while once I have paused music, the hissing goes away completely. Once I resume playing the song (Spotify, Youtube, etc), the hiss comes right back. If I close Spotify or the tab that has Youtube, the hiss disappears instantly. I'm using the Zen DAC solely powered by USB. This happens with multiple USB ports on my computer.
I don't think I've noticed this when using SE. And both of the IEMs I noticed this with aren't particularly sensitive, either (KZ DQ6 and CCA CSN).
Is it normal to get some perceivable hissing/background static when using a balanced connection?