Performance Features Ergonomics Value PRICE $299 AT A GLANCE Plus Outstanding sound from compact solution Ample dynamics for a broad range of headphones Minus 96kHz maximum PCM sampling rate Requires extra-cost adapter for use with Apple Lightning devices THE VERDICT AudioQuest's Headphone amp/DAC-on-a-stick offers sonics to rival standard-size components. Listeners tend to consider an external digital-to-analog converter as either completely unnecessary or absolutely essential. If you believe bits is bits, you're probably perfectly happy with the converter inside your smartphone, tablet, or computer. If you don't, you likely have auditioned many a converter component with a seriously gimlet ear. Both tribes, however, can agree that the headphone amps in most smartphones, tablets, laptops, and desktops leave a lot to be desired when it comes to peak output, dynamics, and inherent sonic quality.