This is unclear IMO. The big issue for some Mk 2 owners is noises (of varying loudness), usually when transitioning from a PCM track to a DSD track or vice versa. Some people, like @amsco15, apparently get noise while playing. Which does this update address?
Please note, the Dsd hissing doesn’t always happen. When it does, it happens during transitions (DSD to Dsd). Once it starts, it is consistent. Playing any FLAC stops the hissing. The noise is like a white noise.
When opening the release notes, you can read what each fix means. For now DAC-613 is to ‘Improve muting algorithm to help with noise issues’.
Further down the notes, you can see what the previous fixes were. The one before last being: ‘DAC-591 Fix settings update process when updating to 2.5.0’.
Yes it is a new download with new FPGA_228 as part of it. Using Windows 10 I have downloaded previous Firmware versions and unzipped them with no problems, but for some reason after downloading the FPGA_228 bin file refuses to unzip. The other files unzip with no problem.