Well, Shunyata recommend that before one buys their system one should start with a basic grounding system, otherwise one would not be able to see the difference objectively. Id est, if you go out and buy their system you may hear a huge improvement, but alas that improvement was because your system had ground noise that could have been fixed by any cheap grounding system. They even have a free PDF guide you can use to help you achieve consistent results by measuring signal ground to chassis ground, and so forth.
I thought it was refreshing to hear such honest advice, and I took it.
I bought a solid copper ground bar with solid copper posts and wired up my own OCC 16 gauge ground wires that are all 4' long. Total cost was less than $300. I wired this into the back of my Shunyata Denali.
I had an obsessively well-grounded system to start, with an isolated ground that goes into the ground behind my gear rack. So I was not expecting much improvement by adding star grounding to my components. My system is also in a room that is thoroughly well treated with acoustic panels on the walls and diffusors on the ceilings, and gear that most would consider to be respectable.
(My disclaimer to the trolls: If you don't have a well-treated room, the benefits of improving system ground will be masked by your room that is full of acoustic noise. Remove the plank from your own eye before you criticize the speck in your brother's eye.)
As promised by Shunyata, this initial system did make an audible improvement which I believe could easily be measured in the S/N ratio because it is eliminating very low level ground loop-type noise.
(Another disclaimer to the trolls: People who consider products like this usually have already blown thousands and thousands of dollars on acoustic treatments for their listening rooms. Think on that for a while before you comment. Thank you.)
So, I can say that following Shunyata's PDF instructions on how to set up your grounding bar works flawlessly. I believe even the cheapest high-conductivity copper wire all run to a star ground will help to reduce measurable ground noise in any system.
That all being said, my cheap grounding system, set up per Shunyata's instructions, was a modest improvement in making the black silence between notes blacker, and revealing more detail in the sound. It was not just making the sound "different" but was definitively an improvement. It just sounded cleaner.
So, while I'm not providing a true report on the Shunyata Altaira, I can say that following their advice (to install a star grounding / external ground bus system like they recommend) is a cheap and highly recommended step in the right direction for any of us who would even consider an Altaira.
Halz