Help! DOS 2.12.5 rollback to 2.11.5

[itgeek77]

Hi there, I upgraded DOS of my Phantom Classic to 2.12.5 recently, even though stability has been improved a bit (still not perfect), I don't like the sound profile of new DOS - sound is less implosive and less dynamic (my personal opinion), it's very obvious when I used it to watch movies or play PS4 games. I really want to rollback the DOS to 2.11.5 although it doesn't support new features but I'm stuck of doing it because I only can rollback to 2.12.3  . Anyone here knows the way of rolling it back to 2.11.5? Your help is really appreciated!