How to bring a fader exactly to unity gain.

UC Surface on a computer makes this possible and it's really simple. This is what holding ALT or CTRL and a click on a fader does:

-> ALT + Click Fader = Fader at Unity
-> CTRL + Click Fader = Fader at Infinity

By the way, this works for EVERYTHING which is using a fader: inputs, outputs, sends, returns. Very helpful for studio work, but also a nice feature for live work. Sometimes it's good to KNOW that the faders are set absolutely exact...