Mini speakers & subwofer
As a suggestion, perhaps consider something like a car stereo with mini speakers (boxes about, say, 7 or 8 inches high) with a subwofer (put under the chart table?). Get the car stereo with a remote control and a remote CD changer. Try to install the stereo without cutting a large hole in the teak. The high frequency tweters are very directional whereas the subwofer is omni directional. Mid range somewhere inbetween.