Makes a loud pitch noise

Batteries lasted all day, worked flawlessly and is quiet (low noise).

but i was plugged into the micro usb power and it would sometimes have static noise on idle without sound until i turned it off and on again.

It is clear that the ‘white noise’ is a electronic interference issue that runs from the power source, whether battery or usb line

You just have to turn down the gain control to eliminate static noise when first using it.

When plugged into my powered speaker with volume on speaker turned up high, there was a noticeable increase in hiss (white noise) when the mixer's master was turned up

UpdateI got email from the seller, suggesting that static noise can be caused by low quality power supply

Output signal contains a lot of static noise when master volume set to value higher than 1/10

Just in testing I'd get horrible feedback and noise after 30 minutes or so on battery power

Connecting input source (electric violin in my case) doesn't change amount of static noise in output

There's a lot of reviews with bad noise.

If it can't function without excessive noise while running off AAA batteries