Charge this device before you leave for the weekend, and you’ll have eight hours of music for the crag or campsite. Link your smartphone via Bluetooth to conjure anything from your playlist. “Surprisingly deep and rich,” said one tester. The integrated solar panels recharge the unit (takes roughly 30 minutes to get enough juice to start playing tunes) and your phone with the included USB port. Warning: It wasn’t fatal, but our unit melted a bit in the hot summer sun.