Most vacuums put out more crap than they take in, unless they are TRUE hepa rated, which are several hundred $ -
Short term, the way I got around it is I went to an industrial hose and coupling supply and bought a 30 foot extension hose for my shop vac - when I vacuum gear, I put the shop vac outside and run the hose thru the door or a window, so the exhaust goes somewhere besides back into the room.
The other thing I did was buy 4 2" soft paint brushes and taped them around an extension wand, to make a softer dusting brush so it doesn't scratch the LCD panels, etc -
It's not good to use compressed air for dusting, especially for a mixer - the faders are usually the most susceptible to dust getting into the slots, and the more dust they get the sooner they will fail (Snap, Crackle, Pop)
Ideally, a built-in vacuum system is best - that way, the exhaust ALWAYS goes outside.
Other than that, the thin painter's plastic drop cloths seem to conform to gear better and keep out more dust when not using the studio. My setup consists of an analog tape rack on one side of the mix desk and an identical rack for procs on the other, with separate key stack and E-drum kit - each separate "island" gets its own drop cloth when I'm not using it. I take the cloths outside when I want to shake them off.
What can I say? "All we are is dust in the wind"... Steve