Back in the day there used to be lots of speaker docks for iPods and iPhones. Now we get Grace Digital's CastDock X2 ($150), a speaker dock for Google's highly-rated Chromecast Audio Wi-Fi streaming device.
I've been playing around with it for the last few days and it certainly is an elegant solution for integrating a Chromecast Audio unit -- sold separately for $30 -- right into a speaker (you usually have to attach it to an audio input and have it sit outside the speaker).
What's nice is that the dock has a Micro-USB connector that provides power to the Chromecast Audio and an optical audio cable creates a digital connection. However, I should note that this isn't a portable speaker with a built-in rechargeable battery. Rather, it has to be plugged in.
As for the sound, it's decent but not exceptionally good for a $150 speaker (it plays loud and has some kick to its bass -- it's just not the most well-defined bass).
The WiFi connection is supposed to provide higher-quality sound but in a speaker this compact, you don't get much of a performance bump over Bluetooth. And weirdly, the speaker doesn't seem to offer a Bluetooth connection, which means you have to buy a Chromecast Audio to wirelessly stream music to it.
According to Grace Digital, here are the key features incorporated into the CastDock X2 and Chromecast Audio (sold separately):
CastDock X2's specifications: