and if you have on screen faders, not all monitors support multi-touch so pulling one up and one down at the same time is impossible. Real faders can do this, but if they don't move, you end up with the physical fader at the wrong position when you start playing tracks from somewhere else - if they all jump to the correct place life is easier. Many people now use either fader panels or mixers with moving faders and once you have them, you won't go back to the old ways.