For audio I use a Schiit Modi DAC and Schiit Magni amplifier attached to some Beyerdynamic DT 770s, this setup is connected to my system via USB. For the past few months I have been having an issue where if my system goes to sleep and needs to be awoken by pressing the power button my headphones start making a very loud, constantly repeating sound. No other audio goes through the headphones, and turning the DAC/Amp off and back on again doesn't help. I can switch my audio over to the motherboard and it sounds fine, but when reverting to the DAC it keeps making the same noise,he only way to stop it is to restart my system. It only started recently, as I have been using this audio setup for several years now. Any idea what could be causing it? Here is a video with the sound the headphones make when I wake my computer, it isn't too loud in the video but it is almost unbearable if wearing the headphones. Please ignore my dusty mouse mat.