Have you ever heard of the disclaimer "technical specifications subject to change without prior notice" that comes with EVERY electronic product?
RME changed the chip to a 99% compatible and slightly better one, so what? And after the fire, used yet another one and went through all the trouble to keep the product 100% the same. It's NOT of our business to know the inner details, as those are irrelevant.
ESS and AKM behave very differently, so it would be good to indicate it in the model number.
Typically, those who insist to know these details are also the most clueless about what these details actually mean... only real design engineers need to apply here, and that's why manufacturers don't ship the detailed schematic and bill of materials (besides the IP concerns) ;-)
Ah good old days, when TV's came with full schematics. Philips had the habit for long time for their electronics to bundle schematics.