Sony's Tomoaki "Tomo" Sato gave me an inside look at his latest masterpiece, the DMP-Z1 digital music player. A powerful high-res player that defies portable audio convention: I've held, operated, heard, and even looked under the hood of the rock-solid Sony DMP-Z1 digital music player - and I'm still not quite sure how to classify it. It sports the look and feel of a high-performance desktop headphone amp/DAC . Yet it runs on rechargeable batteries and stores high-resolution digital audio files, so you can more easily take it from place to place.