The 'ALL' is a final volume control, originally put there for controlling the overall volume of the MIDI tracks prior to PT getting audio features. (RB is based on the PT program).

Most of us just leave that at 100% and don't touch it, controlling the tracks by individual track volumes instead. It can be used to control the feeds to the final outs still.

As jford pointed out, the 'A1' slots at the bottom right of the mixer panel are where the final output FX are inserted.

Those other availabe slots (A2-8) can be used as either final output FX and controls for multiple output soundcards (when available) or they can be assigned as 'subgroups' to control a certain set of tracks. This is another often overlooked feature in RB. They then become labeled 'S' instead of 'A'.
It is a very flexible mixer.


I do not work here, but the benefits are still awesome
Make your sound your own!