Reply to Hiss On Xone 4D, is it normal?

I'm getting to know my way around a newly acquired Xone 4d & I've noticed that there's an audible hiss/slightly static like sound coming through the 4 channels when going through the soundcard as opposed to the phono line in's
when I move the faders up & no audio is playing.
So in other words the noise floor appears to be raised when going through the sound card.
Is this normal or should I have it looked at.