Controlling Volume
The volume of both channels can either be set individually, or for 
both channels at the same time. The volume can be set as an absolute 
value (ideal for gain staging), or relative to the knob position 
(best for adjusting the overall volume without changing MIDI 
programming).

Ch.A  Ch.B  Ch.A+B  Value  Function
20    40    60     0-127   Volume of respective channel. 0 = Mute, 
                           64 = Unitiy Gain, 
                           127 = +32dB (at +6dB input sensitivity)
                           Overrides the setting of the knob.

29    49    69     0-127   Volume of respective channel relative to 
                           the setting of the knob, i.e. CC 69 127 
                           results in the volume according to the 
                           setting of the knobs. For example: Knob 
                           at 12 o clock, CC 69 127 results in unity 
                           gain. (only version 1.0.1)