Sure, tasker can do that (indirectly). It can respond to a change of any/all of the Android volume variables (media volume, ringer volume, call volume, alarm volume etc depending on context). If you want "double click" of volume, you could program the logic in tasker to respond (only) to two decreases of the same volume variable in a short period of time. You could perhaps add some logic to restore volume to what it was before the double volume down. This wouldn't work if volume was already at/near the minimum.