Surely it's much quicker to do this via the track view where all your controls are laid out in front of you.
I'm not bashing Stoons, but your method would involve creating an envelope where none previously existed.
I'd start by creating a new "monitor" bus (assigning it's output to a spare pair on your interface)
Then, select all your tracks (or the ones you want in the monitor mix) and insert a send on these to your new bus all in one go.
Then in track view set your send volume/pan to the same as the track volume/pan.
Of course - if you DO have extensive automation in any track then this automation should then be duplicated on the sends.
I can't think of a quicker way, other than doing it via your busses - run one out for drums, one for bass, one for guitars etc. Far less to worry about, and if it's only for a headphone/monitor mix, then who cares that the balance isn't exactly spot on?