We live in the era of the wireless speaker. I say that not only because of the proliferation of Sonos and its clones. Nor am I talking about Bluetooth speakers, which have become the default music-playback option for most folks. What makes me think that the wireless category has finally, truly arrived are new options from companies such as Dynaudio and Devialet -- wireless, powered speakers that provide high-performance alternatives to traditional wired hi-fi systems.