A brief primer on AirPlay: as a replacement for AirTunes, the wireless audio streaming technology Apple developed for its AirPort Express routers and first-generation Apple TVs, AirPlay uses Wi-Fi to send lossless audio, video, and photos from iOS devices and computers directly to second-generation Apple TVs and various types of accessories. Connect a speaker with AirPlay support to the same Wi-Fi network as your computer, iPad, iPhone, or iPod touch,…