I believe the answer is in the description on the product page.
Preamps are simple things, at least in concept. The Moreplay is no exception; the gain stage is a single 6V6 beam tetrode, wired as a triode. But the devil is always in the details, and this preamp is no exception there, either. Many of those details were chosen to maximize the signal to noise ratio in a wide variety of situations.
Paul Joppa and Paul Birkeland used their many years of experience with the previous designs and developed the Moreplay.
Good, dedicated engineers backed by many years of trial and error design. I think all superb products, like BH gear, usually follow this practice.