Right now only japanese manual is available. English version will probably be available by tomorrow.
Gain switch won't have any effect unless you turn off Typhoon and turn it on again.
Here is some summary of each switch position on Typhoon.
You can download manual from this link when it become available.
Thanks guys for the help :)
Right now I'm doing some experiment regarding the gain switch, still can't differ both :(
I'm using DT770 Pro/80 Ohm