A tip for mp3 files:
This may not be for everyone, but thought I would share it.
I have a TON of music/audio book files on my computer hard drive, ripped at highest quality. The problem is how to compress them so they fit on the USB drive to put in the car, and still have decent audio quality. I found a pretty painless way to do it: using Google Play music.
For years I have been using the free version of GPM. You can upload 50,000 of your own tracks to it ( for the time being anyway, after many years, they have announced they will be melding GPM with YouTube audio sometime in future, and no word on whether they will retain the feature to store your own music for free) very easily, by using their GPM Music Manager app. Select your file folders, hit upload, and it's done, with a really nice interface.
The beauty is that GPM automatically compresses your audio files a lot, but I can tell you it does a fantastic job, and it sounds *great* through the Clarity stereo. Once your GPM library is set up, it is very easy to download the kit and kaboodle back to a folder on your computer, and from there to your USB drive. The file folders are recognized by the Clarity - you can even use the voice command button on the steering wheel to call up by band name, or album name and it plays!
I have literally thousands of hours worth of music and audio books files on, IIRC, a 32 GB USB drive, and it is only halfway filled. That's probably ten times more content than I could have loaded with the full-rez audio files, and it was easy. Plus, if you are new to GPM - it's great. Your entire audio library available to you at any time anywhere in the world for streaming, or download, with zero commercials, for free.