I plug a portable Sirius unit into my amp once and a while, via the headphone jack, and it sounds great. I picked up a pair of wakeboard tower speakers in the off season on eBay and they sound amazing. They have adjustable tweeters so you can aim them down at the drivers seat. You can see the speaker hanging from the rail on the T-top. They are tucked up high and well protected. The Sirius really helps pass the time when your waiting for a bite.
Bob