Updated: How To Control TV with Google Home & Harmony Hub
Google recently released official support for the Logitech Harmony Hub. This means the hubs can be linked together directly without the need for third party apps and hubs such as IFTTT and Smartthings. However, linking the hubs directly will only allow you to control 1 hub. If you need to control more than 1 hub you will need to use another solution such as IFTTT, Smartthings, or another method of control.
How To Control TV with Google Home
This is a guide to controlling your TV using Google Home with the Logitech Harmony Hub and IFTTT. There is also a brief overview for controlling your TV with the Google Chromecast. The best way to control your TV with the Google Home is with the Harmony Hub. In order to configure this, you must use the IFTTT app, which allows Google Home to communicate with the Harmony Hub. Another alternative is using a SmartThings Hub to allow the two hubs to communicate.
Unfortunately, control is limited to starting/stopping an activity. You are not able to control volume or directly tune to favorite channels like you can with the Amazon Echo.
How To Control TV with Alexa
This is a brief tutorial for controlling your TV, stereo, and other devices using your voice with the Amazon Echo. This requires an Amazon Echo or New Echo Dot, and a Logitech Harmony Hub. This video has a step by step guide for integrating these devices for voice control. It also explains how to allow Alexa to control more than one Harmony Hub.
The Alexa app has recently been updated with a new Harmony skill that allows volume and pause/ff/rwd voice controls. It's a little tricky to use but not too difficult once you understand how it works but this overview will help.
Chromecast Audio Review
This is a quick review of the Chromecast Audio. Chromecast Audio works and looks much like the Chromecast for Video. However, it is used specifically for audio. It can be connected to any speaker using its 3.5mm audio port. The port supports analog and digital signals. Digital audio requires a Toslink-to-Mini-Toslink cable. It also supports Whole Home Audio, which works very well as a cheap alternative to Sonos. Once you have it plugged in all you do is open your favorite music app such as: Spotify, Pandora, Tidal, Amazon Prime Music, etc and tap the Cast button. To my surprise it actually plays the music in sync and works well as a cheap alternative to Sonos if you already have speakers around your house.