New Fiio E10 user here.
Couple with Senn HD-558

I do notice low humming at background when music not playing. Any tip to solve it?

I using Macbook Pro 13 with the long charging cable that have grounding.
Also using test pen to check the laptop body (not sure this method can check or not ) Any tip to check grounding?
Did some google search, some said change to better USB cable with ferrite bead. But some said it doesnt work.

Finally decide to send back my E10 for warranty claim. The humming/static noise on left channels (when no music playing) getting more noticeable.
Try on couple of PC/Laptops..still same.
Most likely faulty on that unit.

Any E10 user have such problem?

I had tried different USB cables, Different laptop/PC, Different headphone from Senn558, UE Triple.fi to normal iphone earphone. All same result, left channels had distortion noise when no background music/sound

It started when I first get it. Think it will goes away over time. But it getting more obvious and louder.

But good new is, I got my new replacement yesterday from the shop I brought within few days after I sent to them. Now this set is no more such problem. Will let it ran continuous for couple days.

Kudos to the shop (in Bangkok) that replace 1 to 1.