@thought9
Sorry I can’t tell you whether designs are fully differential or not, I make decisions on sound quality.
If you have five different designers, they can make a particular design sound completely different depending on the sound they want, the components they use, and all the ancillary components.
I know it is tempting to favor a particular design… but a great audio designer crafts the sound using everything from the case construction, the sound quality of each resistor, capacitor, tube, etc. choice. These guys are artists with science and engineering as their pallets.
These great companies have invested decades in research and development to achieve their sonic objectives, using what every technology that can get them there.