@helomech
It doesn’t help that it received a rather scathing review by ASR. That and both ASR and Stereophile measurements reveal the Sphinx falls considerably short of meeting its claimed power spec.
Amir at ASR predominately does not listen to the products he measures. It is also well known in ASR forums that tube amps/preamps do not measure as well as SS, due to the added distortion that tubes provide.
I would also point out that if you actually study where this amp falls with others in his measurements graph, you will notice that tube amps are on the lower end of measurements (again they add distortion which does not "measure" well but that is the point for buyers) and that the best measuring devices are pretty much in the order of cost. While there are exceptions to every rule, a more expensive amp will measure better than one that is less expensive. Not surprising. In fact, most of what Amir comes up with is not surprising, but it does instigate chatter.
As for Stereophile, longtime reviewer Herb R. reviewed it (listened to it) and finished his view with this quote:
I promise, you have my word: The Rogue Sphinx V3 will someday be remembered, like the original NAD 3020 integrated amp, as one of the greatest high-value audio products of all time.
Per his analysis, the Rogue Sphinx excels in the phono stage and headphone amp sections. This is typical of all Rogue products. You get what you pay for.
Also, while the two tubes in the Sphinx are at the input stage, and not the output, changing out those tubes does elevate the sound.
On a personal note, I had a Prima Luna Preamp for a couple of years. Enjoyed it, but was not in love with the sound or synergy that it gave to my SS amps. Amir had measured it’s predecessor, the Dialogue, a year before and panned it.
About two years ago I was able to sell the Prima Luna I had for a fair amount more than I had paid for it. A first in my journey of buying and selling audiophile equipment! While there is some truth in that the turnover of that piece of gear was pandemic related, Prima Luna products have gone up in price because they are wildly popular, even though they do not measure well.