Used Boombox On Ebay I Want To Use A 12v 5 Watt Solar Batt Charger To Power My Sirius Boombox. How Can I Do This?

I want to use a 12v 5 watt solar batt charger to power my sirius boombox. How can I do this? - used boombox on ebay

I'm trying a way to my Sirius satellite boom box will find the use of solar energy. I thought the panel offers harborfreight.com 12V 5 Watt (ITEM 41144-0VGA) with my boombox (SUBX2.) The only problem I see is the input voltage of 12V 3 amps, where solar boombox is 5 amperes. How ampreage?