Interesting experiment.

Let's say I am experiencing background noise of 3 on a scale of 1 to 10 through headphones played through my amp from my PC. Volume on the RR2150 set at 50%.

I unplugged the USB cable from my desktop computer and the noise drops to 0. I plugged the cable into my laptop and INITIALLY the noise is 1, but after 5 to 10 seconds increases to 2, slightly less than the desktop, but still there. I then plugged the cable back into my desktop and the noise starts at 1 (like initially from the laptop) and in 5 seconds goes back up to 3.

I notice when I move the wheel on my wireless mouse feeding to the desktop, I get an increase in noise as the wheel turns. I also notice when I plug the cable directly into a USB port on the computer that there is more noise (perhaps a 4) than when I have it plugged into the "Plugable USB 2.0 10-port hub" that is plugged directly into the computer. This is likely because the power supply of my computer is noisier than the independent power supply powering my USB hub.

So from this experiment I conclude the following:
* Some noise comes from my PC
* Some noise comes from the cable and/or my laptop.

Is there any fix for noise coming from a PC USB output?

I have ordered a package of clip on cable chokes to install onto my USB cable. I'll be trying that by Friday and let you know the results. Someone suggested getting a set big enough so that I can wrap the cable around it 2 or 3 times. Does anyone know anything about the science behind that?

My next step is to spring for better cable.