If my experience is anything to go by it's not the card but the OS - specifically W7 64 bit. There are so many stories out there about sound issues with this OS when using either a USB DAC or soundcard running direct digital streaming such as Kernel Streaming. From what I can gather (and backed up by two of the posts here (#8 and #10) it can be generated by somrthing as simple as a mouse click). My experience again tells me that this is possibly caused by the way that the OS handle its power issues and something that MS has included in the 64 bit version of W7 to give a more 'greener' power consumption can cause these issues. However, nobody has directly identified what the specific cause is. With that in mind you might want to try this.
Go to the "Power Options' on your control panel and turn off any power saving settings whatsoever. You can find this in the guide below
It might make all the difference.
Yeah, I use 64 bit version of win 7, but I don't have a problem with power saving.
The last time I got the awful screeching, it was while enabling / disabling some dsp inside foobar, in order to compare the difference.
The good news is, if I become deaf, my wallet would feel better.