The Reverse RIAA loaned to me, was a Hagerman design, so yes the link is possibly the exact same.
Note: The advice for use, was to be at low volume, so I must reiterate what I was advised.
When the Phon' referred to was being designed/built, the EE who was going through the motions of trialling different components and was allowing the added parts to be used for multiple days via the Reverse RIAA, prior to making an assessment against the running in parallel second prototype. When significant improvements was discovered, I was invited along to experience both Prototypes.
That was a very interesting year in relation to making a new addition for the Vinyl Sources supporting electronics.
The present commission built SS Phon' soon to be received. Is one I am very familiar with as a version of the design, I have heard it in use from the conceptual version - working prototype - offered design. I do not feel the need to be present to make an assessment of the build as it evolves to the finish, I trust the designer/builder is to put in place a tweak to the design that allows my preferences for the voicing / structure of sound to manifest.