Yes indeed,
that were two master volumes with a mini switch to toggle between two settings.
You can clearly hear and see that in the video when the song goes into the quieter mid part
and where he is fading out with that subtle bass lines.
As for the settings he mainly had everything full on on the bass but on different songs
the treble vol rolled back a bit.
Generally the bass settings are not that important for achieving his sound.
Greetz
Oliver (Spyderman)