Grace Digital CastDock X2 - Chromecast Audio Speaker Dock Integrated digital fiber optical connection to suppose 24-bit, 192-khz lossless sound with Chromecast Audio Powers on automatically when you start streaming music from your smartphone and powers down when you are done Group for multi-room or stereo sound Digital class D 50 watt amplifier Includes Castdock Speaker, 18v AC power adapter and user guide