Audiobb, I think in that scenario USB Disruptor would not be needed at all. The power would come from the DAC itself, just a 5 volt lead. And The DAC maker could leave the 5 volt pin off the USB connector on the DAC to guarantee dirty USB power can't leak into the DAC from the computer. I would bet that some DAC makers have figured out the problem and basically install a USB Disruptor type solution inside the DAC, which would be a great way to make a great sounding DAC, and then charge a big dollar amount because the sound is very different, and it's obvious to everyone that it simply sounds different. I'm serious, the sound with USB Disruptor is different.
In my opinion, and to my ears, the sound with USB Disruptor through my reference setup is the best sound I've produced in 25 years, and I think it's the best sound I've ever heard, on any system. It's not loud, I mean I could spend more to add 8 additional speaker drivers and more amps but that would only make it louder - it would provide no more clarity or detail.
I'm a total minimalist with the analog section of my system, having abandoned chunky preamps in favor of a single input passive preamp. The passive pre utilizes a state-of-the-art stepped attenuator, which is a volume control, but the signal passes through a single resistor only, and the volume control has 27 positions each with a single resistor for each level, so the total is 27 resistors. Bottom line on this, the signal is passing through what may be an absolute minimum in terms of volume, and for sure in terms of the preamp since there are no preamp circuits. It's hard to imagine a more pure circuit.
After the pre it goes to my custom Odyssey amp, then to my Von Schweikerts.
Again, it's hard for me to imagine a better sound - the Scanspeak drivers in the Von Schweikerts and the Sanken transistors in the Odyssey are found in some of the most expensive and best sounding audiophile gear- at any price. Buying another amp of similar quality, just more powerful, wouldn't help me do anything but go louder.
The point of this is that I didn't use USB Disruptor in this system until recently. And because of the difference I now know the cause of my digital woes to be dirty USB power.
Had USB Disruptor been invented years ago I may not have upgraded my Adcom amps or Mirage speakers, because the problem I was trying to solve, unbeknownst to me at the time, is caused by dirty USB power. The symptoms include shrill or sharp tones, a kind of graininess to the sound at times, and the silent spaces between notes are often lost. This becomes maddeningly apparent after using USB Disruptor, and I can't think of a single audiophile upgrade that accomplishes so much for so little cash.