Update:This adds a TON of noise, to the point where I've just unplugged it for good. I love the idea of this. Business opportunity for some manufacturer that can produce a working version of this. This ain't it unfortunately.Original review:My use case is I have a 2018 Macbook Pro, an Echo Input, and a Win10 gaming PC all going to one set of modest speakers. I thought I'd gotten a lemon at first, because if I had my laptop and PC plugged in at the same time, I got 50% white noise for those two, See full review