key:
words as high,low
CS Control Selector (wValue field)
CN Channel Number
For CS, zero means undefined

unit type   bRequest    wValue      wValue-CS   wIndex      wLength     Data

selector    SET/GET     0           0           unit,if     1           pin
feature     SET/GET     CS,CN       MUTE 1      unit,if     1           T/F
feature     SET/GET     CS,CN       VOL  2      unit,if     2           1/256 dB steps
feature     SET/GET     CS,CN       BASS 3      unit,if     1           0.25 dB steps
feature     SET/GET     CS,CN       TREB 5      unit,if     1           0.25 dB steps
process3D   SET/GET     CS          ENABLE 1    unit,if     1           T/F
process3D   SET/GET     CS          SPACE  3    unit,if     1           0-255
processMIX  SET/GET     CS          ENABLE 1    unit,if     1           T/F
processMIX  SET/GET     CS          MODE   2    unit,if     1           mode
extension   SET/GET     CS          ENABLE 1    unit,if     1           T/F