Wrap the speaker wires with a twist tie to keep them out of the way.
Remove the metal or wood accent trim with a putty knife and cut the foam away from the veneer with a utility knife.
Apply heat to one corner of the speaker box, where the veneer edge is, with a hair dryer to loosen the glue.
Position a putty knife under the edge of the veneer and lift the veneer from the speaker box. Depending on the type of adhesive used the veneer will come off in strips or small chunks. Continue heating and scraping the old veneer until it is all removed.
Remove the veneer glue by sanding the entire speaker box with 80-grit sandpaper.
Sand the entire box with 160-grit sandpaper to remove any sanding marks left by the 80-grit paper.
Sand the box again with 320-grit sandpaper to completely smooth the speaker box surface.
Remove the sanding dust by wiping the box with a damp cloth. Allow the box to dry for 30 minutes.
Seal the surface of the box with a light coat of polyurethane applied with a paintbrush. Allow the speaker box to dry for 24 hours.
Place the speaker box on a clean, dry work surface where the temperature is at least 70 degrees F.
Cut four pieces of new PSA veneer with a utility knife and a yardstick as a guide, so that they are 1/2 inch larger in dimension than the speaker box front, back and sides.
Remove the protective paper from the back of the veneer and press the front piece into position onto the box and apply pressure with a stiff-bladed scraping tool, from the center out, to seat the veneer.
Trim the excess veneer from the box with a sharp razor knife.
Turn the speaker box and continue placing, seating and trimming the new veneer on the sides and back.
Turn the speaker box so that the front is up and cut the speaker opening out with a sharp razor knife.
Stain the new veneer by applying a consistent coat of stain to it with a roller brush, then wait five minutes and wipe it off with a clean cloth.
Apply three light coats of polyurethane to the speaker with a paintbrush. Allow each coat to dry for 30 minutes before continuing to the next coat or handling the box.
Replace the speaker foam and reinstall the trim.