It is this one, right: https://dandagostino.com/products/relentless-preamplifier?
Its description doesn’t make much sense to me. For instance:
"The audio circuit topology starts with a new discrete differential FET input stage featuring a voltage input signal capability of an extraordinary 30 volts."
Why would one want 30 volts of input sensitivity? For XLR input, a sensible default would be 0.775 volts, for RCA 0.250 volts.
It is fashionable these days to go up to 4.0 volts and 2.0 volts correspondingly for XLR and RCA, yet 30 volts is just way too high.
Output of, for instance iPad, would be way too low for that, with resulting subjective lack of dynamics.
"All signal gain is realized in the current domain using proprietary multiple-output current mirrors with nearly 30 times the linearity of other designs" .
There is no gain in a current mirror circuit. That is why it is called "mirror". Well, one can argue that a gain of 1.0 is still a gain, yet I would argue that one could also get a passive switch box with passive volume control instead of a bunch of current mirrors, and be done with it.
"Utilizing no negative feedback anywhere ..."
How does it achieve linearity then? Does it use some alien technology amplification components instead of transistors or vacuum tubes? If not, and the input signal swings the whole allowed range, then absence of negative feedback must result in non-trivial distortions.
If the idea is that the expected input voltage is standard, so that the input differential stage operates over a small portion of its range, thus increasing linearity, then the issue of excessive noise arises, subjectively perceived as lack of detail. Unless, of course, the preamp, once again, uses some kind of alien technology for amplification and passive components.
"Total Harmonic Distortion <.006%, 20Hz to 20kHz"
At what input voltage? At what gain setting? Without specifying those, the specified distortion figure isn’t overly informative. The preamplifier may well be nice, yet it also may be both more distorting and noisier than typical professional gear used in mastering studios. Hard to tell from the description and specs.