Decent sound but emits distracting electronic noise

While the sound is decent there are a couple of bad flaws. The worst by far is that while plugged in, either thru USB or AC adapter and playing music the speaker emits an electronic noise. If the speaker turned up enough you can't hear the noise much but for quiet listening it's annoying. The second flaw make the main flaw worse. When running on battery the speaker will not shut off by itself when not playing music. This means that speaker will frequently run out of battery so you have to plug it in to use it and hence have to listen to the noise.

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