De-humidifier is obvious. Also the briefest exposure to seawater is instant death to electronics. My basic questions would be what is the predicted 100 year storm height, including wave-run-up? If ground floor is at 0 and 2nd floor is at 8', you are probably well below storm surge + wave run-up and the least of your worries will be your stereo gear. So I guess, get the best flood insurance you can find. Sorry to rant, but construction/occupation of flood-prone areas is publically subsidized via a government backed flood insurance and its not a cost I think that the rest of society should bear.