Oh MAN,please tell me your kidding,you are kidding right?
Remember that the factory finish is veneer not solid wood,most veneer is very thin,too thin to give the wood a proper sanding,unless you can sand out most of the old finish the new finish will not hold.
Ive seen MANY home made paint jobs on speakers & not once have i seen it turn out looking worth a damm,even if you have a pro paint sprayer & the ability to apply several uniform coats of laquer the finish will be very soft & not at all durrable,one little nick will show up across the room.
On top of that home made paint job speakers become valueless the second you do an art project on them.