I know this is long after the original post, but perhaps somebody else will be interested in what I have found. I just tested the Shunyata Diamondback power cord versus the company's Taipan Helix VX and Venom cords, and tested all these against a no-name 16 gauge shielded cord I had been using for several years with my Cambridge Audio CDP. I was looking to upgrade my CDP power cord, and wanted to do a side by side comparison to see where I hit the point of diminished returns.
The results of this test were a fairly clear hierarchy, with the most expensive cord performing the best. My most surprising finding was how much difference the different cords made in the sound presented by what is a decidedly budget hi fi CD player, and the ability of the Cambridge Audio to "hang" with some very nice and well set up equipment.
Test equipment used (in vender's show room):
Cambridge Audio Azur 640C v2 (mine)
Shunyata Cirrus-IC interconnect
Sim Audio Moon I7 integrated amplifier.
Shunyata Python Helix Alpha Power cord (amp)
Acoustic Zen Absolute speaker cable
Dynaudio Contour S 1.4 speakers on
Dynaudio Stand4 speaker stands
Power from the wall was supplied by a very modest but clean Eichmann powerstrip and connecting cable
For the test, I listened to a broad selection of music that I am very familiar with from acoustic guitar and classical works to jazz standards and high slam hip hop. I listened to all these cuts using my salvaged "parts bin" CDP cord first to set a baseline for the other cords. What I noticed about this cheap cord in this particular system was how dry, compressed and "brittle" the overall sound was. The better resolving gear was not hiding any of the shortcomings of my CDP/power cord combination.
I then switched to the Shunyata Taipan Helix VX, figuring if I was going to hear any difference at all, it would be from an essentially free cord to one listing for more than I paid for my CDP. WOW!! Now that was more like it! I was pleasantly surprised how composed my 640C sounded when fed by this power cord. More detail, smoothness, air between notes, voices and instruments, a broader and deeper soundstage, and deeper but more subtle and defined bass. Much less compression if I turned the sound up, then louder but still good music came out... Interestingly, the sound seemed louder for all cuts played at the same volume using the Taipan. Conclusion This is a very nice power cord for digital applications.
Next I tried the Diamondback. Nearly identical overall sound as the Tiapan through all the music selections I brought. This combination sounded so good, I listened to every sample cut (13 titles) all the way through. The Diamondback had a slightly coarser presentation, but the dynamics, nuance, midrange detail and bass were very close to the 2.5x more expensive Taipan. Bells rung with authority and sustain - and I found it really surprising how well this "budget" cord performed, and surprising how well it and the 640C integrated with the decidedly higher end system components downstream.
I then hooked up the Shunyata Venom power cord to the 640C and listened to two cuts and turned it off. It sounded closer to the parts bin cord than I was interested in hearing. The detail was much improved over the cord I had been using, but there was a fullness missing from the sound, and the overall presentation came off as a little thin or tinny and lacking soudstage depth and width compared to the Taipan and Diamondback cords. Perhaps this cord was not fully broken in?
I bought the Diamondback and am in the process of breaking it in at home. So far, the performance improvement with my modest solid state system in my house is better than I had anticipated, but perhaps not better than I had hoped for. This cord is unleashing untapped potential in my CDP that I had read about but not actually realized in my system to date up till now. The biggest improvement is a more natural and less strident midrange and lower treble, being both smoother and more dynamic at the same time. After hearing my CDP with the Sim and Dynaudio equipment, I have new respect for its capability, and will look to upgrade other parts of my system first.
A quick word about the vendor Tim at Experience Audio in Seattle. He was very patient and let me camp out for the better part of the afternoon in his shop listening to these different power cords driving my own CDP through a good system in a very comfortable environment. His staff was helpful without being patronizing or overbearing. And the power cords were on sale. What more can a person want?