A fascinating read on what type of setup and care it takes to produce quality master clocking products and also what it takes to maintain the calibration and testing to do so;
http://www.cybershaft.jp/clockcal.html
Also,...I've concluded many months of testing with 2 additional OCXO clocks from Cybershaft whose OCXO circuit was even more refined than the OP13+ type 2 unit in my RBOCXO-01 and also with a loaned high-quality Rubidium unit (used to have the Esoteric G-0s but it is no longer in my system so I had to borrow its successor from a friend).
At each step of the way, the idea that lower phase noise (and thus lower harmonic distortion and better Allan Variance (measure of short-term stability) were fundamental to the best musical playback, imaging, sound-staging and realistic playback has been proven as a fact.
In side by side comparisons of OCXO and Rb-based clocking and keeping price
erformance ratio in mind, I found that I preferred, by a large margin, a high-quality OCXO clock circuit's impact on the musical playback experience every time.
The exception to this is a Rb circuit with similarly low phase noise; there seem to be only 1 or 2 that have achieved that ( Esoteric Grandioso G1 and 1 other... )