[jmarsiglio]

So the PCI USB helped reduce the noise by about 50%, but I'm going to buy the USB isolator anyway just because I figured I might as well, don't want it festering in my mind

 

[ClieOS]

That assuming the PCI card itself doesn't pick up any noise in the first place.

 

[extide]

If you go with a USB isolator with a circuit layout like this: 
 
Then you can eliminate a ground loop but NOT the computer noise as the computer noise will still come across the transformer coils.
 
 
You need a USB isolator like this: 
that has a plug for it's own power supply so you aren't getting the dirty power from the pc. This one has 
 
 
a circuit layout similar to the top, except there is only one set of coils, and only the USB signal goes through them, while the power is completely separate. I have found it available for sale here. I plan on getting one at some point and looking for a nice little project box at radio shack to put it in. This should get you a pure digital signal from the pc, and nothing else.

 

[jmarsiglio]

Just wanted to update you guys. The USB isolator from Taiwan fixed everything. No noise at all now. It's much cleaner (visually) as well than radioshacks ground loop isolator. Thanks everyone for your help.

 

[kwatch]

Quote:

Just wanted to update you guys. The USB isolator from Taiwan fixed everything. No noise at all now. It's much cleaner (visually) as well than radioshacks ground loop isolator. Thanks everyone for your help.

Which one did you buy?   Does it require 5v external power?