I was very interested in your writing.
I also purchased the M500, but two days later I suffered from the storm-like noise of DSD2.8 and the distortion of the playback sound on PCM768k.
I tried various settings, but it did not improve.
What kind of files do you get noise when you play?
DSD? PCM? What is the bit rate?
The following is a video of DSD2.8 noise generation. Is it the same phenomenon as your noise?
https://www.amazon.co.jp/gp/product/B07X4FM42B/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1
Eventually I decided it was a defective product and asked Amazon.jjp to return it.
And just returned from Japan to SHENZHEN AUDIO in China.