It means that you can use the Pi as just a display (instead of as a display and an amp at the same time). Normally, when you plug the phone into the Pi, the ph

It means that you can use the Pi as just a display (instead of as a display and an amp at the same time). Normally, when you plug the phone into the Pi, the phone won't play audio anymore. Instead, it asks the Pi to play the audio for it. Normally, that's a good assumption because it's connected to a dedicated head unit that has an amp. Now with this DIY RPi thing, we broke that assumption: the Pi has a bad DAC and doesn't have audio input (and the performance is janky now at times for unknown reasons). I was just tipped by Emil, another developer who got really deep into hacking this. He told me that there are ways for the Pi to say "I'm not interested in helping you project the audio, you just keep playing whatever you normally play." So now your phone only projects the UI/maps to the Pi, but still routes audio/Hands-free directly to your stereo through BT. A benefit of that is you can use your handsfree, buttons/controls built into your steering wheels fine if your car has native Bluetooth. That workaround has some problems with Chinese phones we realized, but works OK for a couple of Nexus/Pixel we tested.