I use PolyPlanar waterproof speaks and waterproof radio MRD60. They have two radios now, a cd player version with a plug in for a MP3 (MRD60) and a straight Ipod dock type (MRD70).
I had to replace mine after 6 years due to internal corrosion and they do not repair the radios. If you are out of warranty, they charged $110 for a new radio but you must send in your old one to "swap out".
Might consider getting the waterproof "housing" that mounts inside the center console space if this is where you mount your's as my 190 gets alot of moisture in there coming up from the inner hull space/bilge. I have been working to seal the console better using different size swimming noodles etc.
Also, some have mounted waterproof ski rack speakers onto their Ttops, Been thinking about a set myself.