EMI driving me *nuts!* No soundcard ; using USB DAC. Help!

[Strat-Mangler]

I've seen this problem occur in many PCs and have never been able to find any solution to this incredibly annoying issue!

I don't make use of a soundcard in my PC. The audio is routed through a USB cable into a DAC (Aune T1) which then plugs via an RCA cable into my stereo amp (Arcam AVR350).

Whenever there's any activity on the hard drive or whenever I scroll a page in a browser, I can very clearly hear some noise stemming from my PC. Some crunchy digital noise. The louder the amp is, the louder the noise is.

So far, I have tried the following ;

- All different USB inputs, including the front ones of my case.
- Changing all cables to shielded ones.
- Even used an active USB cable.
- Used an active USB hub (which people said fixed the issue in some cases).
- Tested the plugs for proper ground. Passed with flying colors.
- Tried plugging other things in the amp. No such issues.

The motherboard is a Gigabyte GA-Z77X-UD3H.

How can I either shield the USB components from routing EMI noise to my DAC?

Or how can I ground it so as to possibly eliminate the issue as per the following post? http://www.overclock.net/t/571718/how-to-make-emi-shielding-for-your-sound-card#post_7139336

HELP!!!!!

 

[gr34td3str0y3r]

your not crazy. Did you ever find a solution by the way. 
I know this might sound crazy. Is it is the sound FROM your PC? 
on my PC the refresh rate of the monitor just not jive with the video card and I read that it will work but the capacitors will screech. 
I hear a nose when I scroll and when I highlight text. How weird is that! 

 

[fccn75]

I was in the same shoes - noise from any digital source causing noise at the output of the amplifier. Many hours of grounding and different physical outlet location did not help until after many searches here and googling, I decided to give this item a try:
 
http://www.ebay.com/itm/HiFimeDIY-USB-Isolator-ADUM4160-5KV-1KV-signal-voltage-isolation-DC-DC-convert-/131315276479?pt=LH_DefaultDomain_0&hash=item1e93001abf
 
This is just one such device that will get rid of the noise but there exist many others that serve similar functions.  I can only tell you about this one because it's the one I used.
 
Basically, it sounds like you are experiencing digital ground loop noise which sounds like two frequencies - one low and one high intermixing resulting in a high pitch buzzing.  It also appears to correspond to mouse movements, hard disk activities, and etc.
 
Only thing to keep in mind is that this USB isolator will limit high rez playback to 24/96K.  The isolator solved my noise problem but I don't like being limited to only 24/96K so I decided to use optical instead, oh well...