I am having the same issue, but with the HS70 Wireless
I noticed it only happen with gaming, I don't know why.
I already tried:
- turning off Window's volume reduction: it didn't work
- disable the Dolby Headphone feature: I don't know where this "Dolby" feature settings is, but since it's been more than a year I assume you were talking about the "7.1 surround" and "2.0 Stereo". And the issue happens with both of them
Anyone figured it out?