Refinish speaker in different color

These, like 99 percent of speakers, are veneer. Veneer can be stripped and restained. You must remove the speakers from the cabinets. Use a remover that doesn't require water for a final wash. Use liberal amounts of stripper with a brush...after finish is liquified, carefully use a plastic putty knife to remove the loosened finish. Repeat if necessary. when majority of finish is removed, recoat the cabinet with stripper and use #3 course steel wood with the grain to remove the remaining finish. If any black color remains in the grain, recoat with stripper again and use a stiff natural bristle brush in the direction of the grain. Finally use the steel wood again with mineral spirits to remove any residue. Finish up with a alcohol wash and a rag. It may very well be that a black lacquer was used instead of stain. Either way you can get the desired results. Sand with 220 paper, wipe with a tack rag and stain. Finish with two or three coats of polyurethane using xxxx steel wool between coats. If you use a water based poly, do not use steel wool, but #320 sandpaper.