Damn, edit time expired. So the digital display one came from the incompetent boob. I almost feel bad for the feedback I left for him. But, its now 6 days PAST the freakin' 6 - 8 weeks he had to deliver. It didn't really piss me off, so much as "how dare you?", when he told me not to worry about something I had paid for and he couldn't account for. I looked for an easy way to change it, eh... not worth it. He's got a good customer rating. Maybe he learned something. I know his tone, switched REAL fast, when I asked for the refund from Amazon, instead of him directly. Plus, since I wanted a red one and the one I ordered from ebay, I could only get in black or blue... Score! (again, this will end up being 2 non-LED units and 2 LED units, for the whopping total of $14... hehehe) This adjustment has a nice bit of restriction on it, display/voltage doesn't jump around, move up and down the spectrum easily and smoothly. Error, is just about .10. Just a nudge past it clicking over to 11.4, is at 11.5 on the multimeter. Nice, bright blue LED display. With another one (blue) on the way. Hope its as accurate and consistent as the first and hopefully, this third one is. After reading this, I realized I'm kind of confusing people and not communicating this right. There are two issues. Shielding and grounding. What you are experiencing with your headphones and other electronics, is caused by an electromagnetic field (EMF). Its invisible, obviously, but if you could see it... it radiates outward and decreases in strength the further it gets, as you've experienced. The sound, is just the hum, made by 120Hz. Its caused by cheap parts, poor manufacturing and QC. You get what you pay for. These vvps are certainly proof of that, though I would say its subjective, in that... what are you willing to put up with. I know isolating it, putting it on circuit protection... its just a nuisance. Actually, unless it malfunctions even operating as it is... it probably won't be an issue. 115v/120Hz, just isn't that much. Final note on the LED model. At least this one.... runs quite a bit hotter than the non-LED. Not burning hot, not even HI hot, really... just hot. During most hours of the day though, its sitting in front of a cooling fan. Not a biggie here.