Unfortunately, the distance from my Mac Pro to my DAC is 15 feet, the theoretical limit of USB 2.0.  Thus, I am concerned that my Amazon USB Cable might not be "sufficient."  (DAC is the Chord Qutest)  I also can believe that there may be validity to isolating (separating) the power from the data lines within the USB Cable.  I would prefer not to spend 2-5K on a USB Cable;  the AUDIOCADABRA is $500 or $1000 depending on model for 15 feet.

Although I would prefer to do my own A-B comparison on my system, this is currently not feasible.  So, I would appreciate hearing the opinions of those who may have personal experience with AUDIOCADABRA cables.

Thank you.

Are you going direct from your PC to your DAC? The reason I asked is have your considered isolating the ‘noise’ from your PC? Something like a iso-regen device would not only provide cleanest signal, it will also eliminate the need for a high quality long length USB cable. Use a generic USB cable between your PC and iso-regen and a short length (1M) high quality USB cable between iso-regen and your DAC.

The short length cable will also allows you the flexibility of A/B comparison between different brands. 
I am going directly from PC to DAC. I thought that anything introduced in the path would potentially decrement the sound quality or at least introduce a change in the sound characteristics.  I may be wrong in that assumption.

I think you will hear a definite uptick in SQ. Please read up on iso-regen and I would encourage you to try it.

It’s a well known fact that audio signal from PC’s is inherently noisy. I wouldn’t waste money on a 15FT high quality USB cable unless you first address the noise.