Here, from the s 970 Reference manual is a list of the functions of the Live Control Knobs. In the manual they are on pg 11-13.

Balance/Song,Audio Adjusts the volume balance between the Song and Audio playback.
Rotating the knob to the left increases the Song volume, while rotating it
to the right increases the Audio (USB Audio Player) volume.
Balance/Song,AUX Adjusts the volume balance between the Song playback and sound input
from the [AUX IN] jack. Rotating the knob to the left increases the Song
playback volume, while rotating it to the right increases the input volume
from the [AUX IN] jack.
Balance/MIDI,AudioAUX Adjusts the volume balance between the playback of MIDI data (Song,
Style, Multi Pad) and Audio (USB Audio Player and input from the
[AUX IN] jack). Rotating the knob to the left increases the MIDI volume,
while rotating it to the right increases the Audio volume.
Filter/Voice,Style Adjusts the cutoff frequency of the filter and the resonance for all keyboard
parts and the Style to change the timbre or tone of the sound.
Reverb/Voice,Style Adjusts the Reverb depth for all keyboard parts and the Style. Rotating
the knob to the right makes it deeper.
Chorus/Voice,Style Adjusts the Chorus depth for all keyboard parts and the Style. Rotating
the knob to the right makes it deeper.
Master Tempo Changes the tempo of the currently selected Style or Song. Rotating the
knob to the left makes it slower, while rotating it to the right makes it
faster. Setting range is from 50% of the default tempo value to 150%.
<No Assign> No function is assigned.

Thanx Eddie for the info....very kool.....
I assume while a song is playing..you can adjust volume of an MP3 with one knob interdependently.......
and MIC Vol with another knob also?...or?

can some one please test this ...?

Yes...you can do any two of many controls anytime...and choose any other controls istantly.

The posted list of controls is not complete. It was 3 pages in the ref manual.