For those who didn't read the patch notes which mention the dongle may be desycned on updating:
The recent firmware and HQ update may have caused a de-sync between your Maxwell and dongle. We have specified in our patch notes that your dongle will likely need to be paired again, so here are the instructions for your convenience!
On your PC or Mac machine, download and install the Audeze HQ software for Mac or Windows
(you must use v80 or higher).
Windows:
https://www.audeze.com/pages/audeze-hq-download-windows
Mac:
https://www.audeze.com/pages/audeze-hq-download-mac
Once you have ensured you are on v80, both the headset and dongle must be updated to V51.
One at a time. Meaning that the headset must be connected via a USB cable to update to V51, then disconnecting the headset, connecting the dongle, and updating that to V51. They are two separate updates, and both must be done. HQ must be on v80.
From this point, we recommend restarting your computer. Once restarted, open up HQ, and from the "Settings" tab in the software, you'll see a button that says "Pair Dongle" (if your dongle is already paired to your headset, you'll have to power your headset OFF before the button will show).
When you click the Pair Dongle button, a new prompt will appear. Follow all on screen instructions to finish dongle pairing.
If this doesn't help, please uninstall and reinstall the Audeze HQ app and try the software method again and this should remedy this issue in most cases.
Hardware fallback:
In case the above pairing instructions do not work, you can re-pair using a button on the dongle.
Insert a paperclip into the small hold on the side of your dongle and click the button once. Once the LED begins to flash, triple tap the power button on your headset. You'll hear a "pairing" voice prompt in the headset.
Your headset may power off and power back on after it re-pairs.