Hi Carlos, indeed I've seen a lot of studio-intended tube devices that take advantage of variable saturation and the like. I've also seen a lot of studio equipment in general- while studio gear in general is often built to a higher level physical construction standard (Studor for example), the component quality in the very best studio gear still sucks. I've rebuilt many pieces with nothing more than improved parts quality and gotten serious improvement without any other modification.
So I do not hold to the idea that studio equipment has *anything* over properly built high end audio gear. In fact, high end audio gear routinely shows the flaws inherent in even the state of the art in studio gear. IMO, engineers designing recording gear could take a hint from high end audio: more tubes, more use of superior materials such as wire, better coupling caps, resistors and so on. I'm afraid that the semi-pro market has eroded a lot of the expectations of studio equipment performance (also IMO) but regardless its a fact that the industry could be turning out dramatically better recordings if they could get the same sort of mind set that high end audiophiles have.
The funny thing is that in the old days (50s) they certainly had that mind set, although back in those days component and materials production was in an embryonic state. Somewhere along the way the recording industry lost it, IMO.