Dépends of your budget !
Watts means nothing, a 4x30wrms Precision Power amp can destroy most of low budget speaker of 300w.
You will need for sure, 2 x 4 channel amp at least, or a 6 channel amp + 1 monochanel class D for the sub.
At least 1x 4 channel to drive in-boat front and rear speakers, 1 other to drive 2 to 4 (connected in parallel) tower speakers + 1 sub.
Becareful to focus on the power of the bridged channel of the sub amp, it as to be 4 times the single channel power. Ex : a 4x50 amp will give good result if it's a 2x200w briged system.
Depends also of your subwoofer. Is it a 4ohms single coil, or twin coil, 2x4Ohms ; 2x2Ohms ?
Marine, not marine amp, it dépends of your budget as well. I prefer cars amps as we have more choice and more quality/power/dynamic range amps.
For a boat, you can go for those band :
Rockford Fosgate ; MTX (not first prices) ; Orion ; Precision Power ; JBL (not first prices) ; JL audio (if you have a good budget ...) etc.
Forget about japaneese, german, Italian things, they will not give high pressure of sound on a boat IMO.
Hope it helps.
Last edited by Sdc77; 05-06-2013 at 04:27 PM.
Stéphane
-----------------------
1989 Supra Saltare