For ages now I have had a small MP3 player inside my Tamiya Sherman that plays All For The Love Of Sunshine and Burning Bridges when im using the tank

but because I have the MP3 player, the battery pack (3 x AA), a switch and the speaker inside room is a little tight and turning the switch and MP3 player on and off is a pain in the ass, What I would like to do is somehow have the music come on when I press a switch on the transmitter (im using 4 channels) and have it powered by the tank battery, so im thinking I need to ditch the MP3 player, but what can I use instead

is there some kind of circuit board you can load audio files on to that can be powered through the tank, but at the same time keeping the tank noises separate, which would mean a second speaker, or does anybody know of a better way of solving my problem
