We ripped out the broken car sound systems and wiring.
we got Anker speakers, these arent waterproof but have survived being in a drybag full of lemonade while on and sitting in a 10cm deep puddle on the bimini roof
we installed USB ports in the walls to power them and wired that into the 12v system
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we use a PRODUCT LINK connected to our pad which is connected to the Starlink to power the sounds for the whole boat.