Hi all, I've had my Schiit Vidar for 2+ years and it's been great, without any of the noise/hum issues I've read about-- until now, when it's developed a particular issue I haven't been able to figure out on my own and can't seem to find specific trouble-shooting advice for when I search this or other forums. To wit, every two minutes or so, whenever the vidar is on (connected to a preamp source or not, playing or not), it emits about 10 seconds of something in between a rattle and hum. If I place my hand on top of the vidar towards the front side of the unit, I can feel a vibration from whatever is producing this noise. This problem started yesterday, and it's worth noting that I had left the vidar on for about 72 hours just previously, which I don't typically do, but my understanding is that lots of other people do with theirs without incident. But maybe that triggered this. I've tried switching out power cord and interconnect, to no avail. I guess the next step is to figure out if it is a ground loop issue? But from what I've read, this doesn't seem like how a ground loop manifests- though I have zero electrical or engineering experience, so I'm learning this stuff on the fly. In any case, I am pretty stumped, so any suggestions or thoughts would be appreciated. Many thanks.