It is JUST FINE to put a reasonable amount of wax on a lacquer finished instrument. (or varnished for that matter) Old editions of The Strad magazine reccommended good old Johnson's paste wax for this precise purpose, but there are several commercial concoctions on the market these days. Bruce Petros at www.petrosguitars.com makes an excellent proprietary polish that contains carnauba wax, a hard vegetable based wax that can be buffed to an incredibly thin coat. If it's good enough for a Stradivarius, it's good enough for a Martin. Make sure to use sparingly and to buff well. And if you do get a buildup, naphtha will remove it nicely without hurting the finish. I have sprayed acres of lacquer (literally) on instruments and furniture and to hear the opinion that wax will hurt a lacquered finish or affect the tone is just a bit precious! It will not appreciably affect the gloss sheen of the finish. 'spaw has it right in the post above, gloss needs to be addressed at the time of spraying.