Sense 6 came with a ton of new features for the HTC One, but for some reason, HTC decided to keep one of them hidden to all non-Harman Kardon editions.
Music Channel is a music visualizer that can also link into the GraceNote music catalog and display lyrics for any compatible songs. While it may not be the most revolutionary feature, it can definitely be a great app to have mirrored to your Chromecast.
Enabling Music Channel is extremely simple thanks for a hack uncovered by XDA member Carl Baker. This process will work for both the M7 and M8, just be sure you have root access and a root-capable file explorer, like ES File Explorer.
We will need to edit a file located at /system/customize/acc/, but to do that, we will first need to make sure ES File Explorer has the right permissions. So from the sidebar, tap Root Explorer -> Mount R/W and make sure /system has RW permission.
After that, open up default.xml from /system/customize/acc/.
Open the file with ES Note Editor, then scroll all the way to the end of the file to find the line that starts with support_music_channel. Change the value to true, save the changes, then reboot your device.
After the reboot, open your Settings app and toggle on Music Channel. Now whenever you play a song through any music app, Music Channel will be activated and will display a visualizer along with the lyrics to your song, as long as GraceNote has it in its library.
This isn't something that you would use everyday, but it can definitely give you some sweet background visualizers when playing music at a party through your Chromecast.