[rdsh]

I noticed the same on my pair of Moondrop Chu II. There is a post on Crowd Supply that talks about the noise floor being picked up by such devices: https://www.crowdsupply.com/cool-tech-zo...io-quality. See "A Hack for Budget IEMs".

Perhaps this is the "hiss" you are talking about. It can be fixed by soldering two small resistors as described in the post.

Personally it doesn't bother me much, and it's only slightly audible during quiet parts of a song.