Controlling / setting the overall "Audio meter / gain" slider in the UI

Hi - I have an installation that's been running for years and has a fixed configuration of multichannel output. For a variety of reasons, some new content is quieter than we'd like, and we find that if we push the "Audio meter / gain" slider (that's what shows in the tooltip when we roll over it) -- the one in the bottom right of the UI frame -- we can raise it a tiny bit past the default 'top' position and this new content sounds good.

Is there a way to programatically set this slider? The installation runs autonomously, and I'd like to send a command to set this slider (we do everything via OSC commands, so that's not an issue)... but is there a max object that controls this final overall output?

Thanks for your help.

<M>