[Android Head-Units] celticchrys:
I installed the Sony XAV-AX200 system in my vehicle a few days ago. Coming from a very traditional car stereo that was not smart in any way, that only did CD, radio, and mp3, this is a very different experience. I've been learning the quirks of this system, and I thought that perhaps if I organized my observations here, it might benefit someone thinking of this system. Feel free to add, answer questions, etc. I intend to update/add as I observe more.

This was installed in a 2004 vehicle with no "smart" anything, no steering wheel controls, nada. My unit has been flashed to the firmware version 1.01, published May 10, 2018, available at the Sony support page.

The Good:

Sounds great

Works well with factory Pioneer amp/speakers/subwoofer.

Decent radio reception

Plays FLAC and mp3 files from usb flash drive

Works with both Android Auto and Car Play

Real volume knob and forward/back buttons

The Quirks:

There is no power button. There is no way to turn this system off. Has anyone ever wired a switch into the power line, to give them a way to actually turn these "smart" stereos off? I'm considering it.

If you do not manually go into a menu, then select to turn off current source, before you turn off the ignition, whatever you had playing last time will auto play when you start the car. There seems to be no way to disable this obnoxious behavior. You just get blasted with whatever, when you turn on the key.

Mp3 and flac files only play from your phone or from a usb flash drive. They will not play from a CD-R disc. This is truly bizarre.

Tips:

Works with a USB 3.0 hub, with a few caveats. I have a small Targus USB 3 hub plugged into the port on the back of the unit, and then two dash ports plugged into the hub. Either a flash drive (full of FLAC files so far) or my Android phone will work if plugged into either dash-mounted port.

However, if you have a flash drive that is hooked up through the hub, playing music, and then you also plug in your Android phone through the hub, Android Auto takes over.

While the music you have already playing from the flash drive will keep playing in the background, and indeed further music files in the folder keep playing (if you don't start playing something from your phone), you lose all access to control the music.

The USB icon disappears from the home screen as long as your Android phone is plugged in.

While the music from the flash drive will keep playing indefinitely (if you don't play media from your phone) when you unplug your phone, the music from the flash drive will stop until you tap the "USB" icon on your home screen, and it will not resume from where it was, but will start at the beginning of the drive, alphabetically.

Album art does work, but you must turn it on in the settings on the unit. Album art displays as a background image while music is playing from a usb drive.

At least on the FLAC files I've been playing, album art only seems to work if it is 400x400 pixels in size or smaller, and is embedded into the file's tags. folder.jpg files in the album folders are ignored, and larger embedded images are also not displayed on the unit.

I had some albums in FLAC format that would not play. This turned to be due to the way they were saved. I had to open them in an audio editing app and export them as 96 kHz, 24 bits files, which is the max this unit can play.