wow..
ok first,, stop rolling your rx, which isn't that easy... are you letting go of the dam handlebars when you are falling off ?
thats another thread, nevermind.. but do that if your not please....
there are water proof audio systems out there, and if you wanna dump 600 ish, your golden, 3 good choices but i won't dig up those links unless you really plan on dumping that much, most people aren't.
otherwise you just need a head with jack and two speakers, water "safe" not waterproof. for sub $200 assuming you know how or who to call to install but that also involved drilling holes.
e with an ipod shuffle and headphones, works great with ear buds but they pull out when jumping wakes. *i've ridde
i occasionally ridn with guys with little radio setups, its nice for a change.
a cheap option of course is buy a little portable battery speaker and plug it into a mp3 player. no wiring or cutting holes in the hull are involved. maybe as you spend more (say spend 70 vs 20 for a battery powered speaker) you'll get better quality.