The Faders are assignable on the O 49.

There is a good chance that someone has already programmed that used O 49 such that one of the faders is sending CC 7 Volume.

So after hooking up and getting it to play so softly on the Thru channel, try moving each fader, one at a time, from bottom to top while playing the keyboard in an effort to see which one may be sending that Volume command.


--Mac