Earth loop - non-reaper question, sorry

Keyboard to laptop via USB Want to mix the signals coming from laptop audio and keyboard audio via, but get terrible whine/buzz/white noise. If I disconnect the USB, the audio signals can be mixed fine. Can anything be done?

First thing to check is where the keyboard and computer are plugged in. I've had issues using power points on opposite sides of a room. Using a power-board from a single outlet solved the problem.

as its a laptop if running purely on batttery power is the noise still there, often laptop power supplies can be the source of the noise also try if possible to use a different usb port on the pc and contrary to what people normally recoommend also try runnung the keybourd through a powered usb hub to the pc

Sorry for not making it clearer, as mentioned in above post, problem solved. Thanks for trying to help.