Apogee Groove is the best portable USB DAC and headphone amp for listening to music on your Mac or PC. Groove takes the same high quality audio technology found in the world's most prestigious recording studios and delivers it to your laptop. Connect Groove directly to your computer and connect your headphones or powered speakers directly to Groove. For 30 years, Apogee has been an innovator and industry leader in digital audio recording. Now Groove makes Apogee sound quality available in a simple take-anywhere device dedicated to delivering the ultimate listening experience. Unlock the full potential of your high-res audio files, rediscover your iTunes library and stream Spotify, Pandora or your favorite music services with incredible clarity and detail. Groove's Constant Current Drive output stage is a truly revolutionary approach to dealing with the wide impedance variations of headphones available on the market today. With Constant Current Drive technology, Groove's output stage's voltage is dynamically molded to the impedance variations of the connected headphones, thereby smoothing out frequency response non-linearity that occurs with traditional headphone outputs. Groove also features a Quad Sum DAC design which employs four digital-to-analog converters per channel to achieve the highest dynamic range and lowest distortion (THD N) of any device in its class.