A little bit late out of the starting gate given the discontinuation of the second-generation iPod shuffle, H2O Audio's Interval ($80) is an update to the iSH2, which combined a hard plastic, watertight iPod shuffle case with a headband and cone-shaped waterproof headphones. Interval removes the headband and replaces the headphones with ones based on Surge, the company's smaller, better canalphones, all while preserving the prior price. It's designed…
