Hey guys-

I have a problem and hopefully this is the place to solve it. I recently purchased an Allen & Heath ZED 10 mixer. I'm using the onboard USB interface straight into the computer. I'm using a Shure SM7B mic. When everything's set up and I'm monitoring just through the mixer, it sounds perfect and crystal clear. Then when I record, there's an extremely loud hiss. It's a high frequency hiss, like a bad cassette tape. Since the noise only happens once recording, the problem must be with the USB. I've been troubleshooting in every way I can think how. I'll list them all here:

-Returned the mixer and got an identical replacement. Still same problem.
-Tried on three different computers, Windows and Mac.
-Tried all channels.
-Tried a different microphone.
-Tried a new USB cable.
-Tried a ground lift adapter.
-Tried using the line in, same hiss.
-Tried different outlets.
-Tried different DAWs.

Really stumped here! Everything I can find says these units sound great. Thanks in advance for the help!!