Audio Grade Internal USB Cards?

Does anyone happen to have any experiences with various internal audio grade USB cards to help improve the digital signal and isolate the DAC from the main USB bus?

I recently purchased a Paul Pang PPA V3 USB card a few months back and have found it to be a very worthy upgrade to my system. Currently it's being fed by an external Linear PSU and the results, in whole, have been well worth it in my opinion.

Lower noise floor, improved detail/dynamics, as well as better overall tone and imaging have been the biggest improvements, but I'm also now confident that my signal is off my motherboard's USB bus as well. I recently had some upgrades installed on my amplifier and unfortunately after doing so I immediately began to hear processing noises from both the bus (mouse/scroll movements) as well as what I believe were noises from CPU usage (opening programs or stress testing) that I do not remember hearing before, nothing else was changed. I'm fairly confident that the noise had always been there, but for some reason, upgrades or not, I was unaware until now.

The noises were not very loud and only noticeable at higher gain and with no music playing, but they were there. I was able to tell that the mouse only created noise when moving it fast, but more noticeably when scrolling, even very slowly. Running my processor at load and disconnecting everything but the power cord and my DAC did nothing to stop or lower what I believe was CPU noise. I also tested the outputs of 3 different machines and the noise was there on all, but at varying intensities with the most expensive and newest motherboard, which also advertises as having better isolation, being the best of the lot. The noises were also present no matter which bus I used, 2.0 or 3.0. To me it was a bit of a struggle as I didn't want these noises contaminating my signal, no matter if it was my DAC or amp that was not filtering them out, etc.

Even though all of this was initially troublesome, it actually was a positive in the end since I was previously unaware of this issue and I had already decided on giving the PPA card a chance. Now I had something to actually look for! Well, to say the least, I'm now positive that the PPA card is isolating the signal from the bus and the processor as I do not have the same noise issues as before and I have switched between my motherboard's connector and the PPA's, same machine, numerous times testing.

If anyone is interested in learning more about this card, below is Paul's informational/store blog:

http://ppaproduct.blogspot.com/2013/07/audio-grade-usb-30-pcie-card.html

I got the Version 3 card, with the OCXO clock attached, and also added the card slot with the cable connected to it to run the linear power into the slot externally and ultimately into the card's Molex connector.

Anyone with similar experiences with this or other cards, such as the SOtM? Where you able to tell/test the isolation differences? Did/do you hear any sonic benefits such as cleaner sound?