I'm afraid the moral of this is don't buy a USB DAC (or any other USB device) that needs proprietary drivers!
Many manufacturers have moved away from developing and maintaining their own device drivers.
I have tried another USB cable, another USB port, have reinstalled-even removed my sound card drivers, have reinstalled the DAC drivers, to no avail.
I still have the disconnection issue with all player applications in any mode (Foobar and JRiver with ASIO, WASAPI), but also with browsers (probably DirectSound?). The solution is to power down and then power up again (so the USB device is found again by Windows) the DAC. Sometimes the disconnections are very frequent (every minute) some others are more rare (every 20-30 minutes or so)
What has made me not call the Support so far is that I never had disconnection issues with PC games. I am still puzzled by this, but then again, I rarely ever play any games at all.. I hava decided to return the device for inspection asap.