keithmarsh
100+ Head-Fier
I didn't write the USB firmware, so I can't give a firm opinion on this. But I contacted Chord last night, and they responded that so far only two reports have been sent to Chord support and so far it suggests that it is a USB sync issue. At the start of sending a track, the source and Mojo 2 communicate to establish sync and set the sample rate. If sync is lost, such as when you break the USB connection, then you can get the noise, which will continue until a re-sync occurs, such as stopping the track and re-starting.
Chord suggests also that the source be set to exclusive mode, as this has fixed source issues.
The only times I have heard this has been when losing USB connection by pulling out the cable and reattaching. Or when you shut down the DAC but keep the source running. Upon restart the source does not re-sync correctly. I always close any source app before shutting down the DAC. It's never happened to me whilst playing a track.
Note that all of the Chord DACs have identical USB firmware and USB decoder.
If you are getting it after having checked the USB cables (use a type 2 certified cable), the USB connections, and confirmed it is in exclusive mode, then I suggest that you email Chord support.
Thanks for the feedback. To your last point - the issue does happen in exclusive mode, with different (good quality) cables and it also happens during playback when no cables have been touched / moved.
As you suggest is would be great if everyone experiencing the issue to contact Chord so it may be investigated a little further.