Replace 12AU7 with 6SN7 ?

Hello Guys !
I own Ayon Triton (integrated, but use only the Power section) with 6 12AU7 an 8 KT88.
I read in some threads that the 12AU7 can be easily replaced by 6SN7 (which I have 4 of them and enjoy in my Preamp).
This to be done by a "socket converter" (available on eBay) which internally makes the required wiring for the filaments to allow the replacement.
The reported results were positive.
I asked the manufacturer the same question and the answer was "straight forward", "quote":

DO not use 6SN7 or any others as the original types are. IMPORTANT – otherwise your amp will be destroyed.

Does anybody have any experience with replacing drivers like 12AU7 to 6SN7 in Pre or Power ?

thanks.