Why an armrest is essential on an acoustic guitar

Most of your guitar's tone comes from the vibration of the top. The average player who doesn't have an armrest on his/her guitar dampens and therefore loses between 15 to 40 percent of the tops vibration depending on where their forearm rests. A properly fitted arm rest ( John Pearce ones are the best I know of, made from beautiful hardwoods like ebony boxwood and rosewood ) will instantly make whatever guitar you have sound better...and like it's true self, eh!