If you've been waiting to be able to play the same song in multiple areas of your home, or support for some higher quality audio from your Chromecast Audio, both of your prayers have been answered. If you've got a Chromecast Audio hooked up to some high quality speakers, you'll be thrilled to see the improvement that brings support of up to 96KHz/24bit lossless audio playback. Additionally, you can now create a group of devices and cast to them so you can be playing the same tunes in various areas.

  • Introducing Hi-Res audio support:Close your eyes and imagine the musician is playing in the room. Today we're rolling out high-resolution audio support, which gives you even higher quality music playback using Chromecast Audio. With support of up to 96KHz/24bit lossless audio playback, you can enjoy higher-than-CD-quality audio on your existing high fidelity audio equipment.
  • Blast the same song in every room: Now you can easily fill every room in your home—bedroom, kitchen, living room, or wherever you have a Chromecast Audio connected—with synchronous music. Multi-room lets you group Chromecast Audio devices together so you can listen to the same song on multiple speakers.

Getting set up is simple. Once you've got all your Chromecast Audio devices connected to your speakers, head to the app and create a group. Once the group is created, you can cast to it the same way you would a single speaker.

Source: Chrome Blog