I've gotten a little farther along. Here's what I discovered so far:
- USB stick needs to be formatted FAT. exFAT (which is the default used by Windows in some cases) doesn't work. You will need to download a utility that will force a FAT format. Just search for 'HP USB Disk Storage Format Tool'
- Once formatted as FAT, you can copy your 192/24 FLAC files to it and the Tesla onboard music app will properly parse the metadata and play back the files. It will disregard any album art. It goes online and grabs its own cover art. Seems to work fine.
- So there are a couple of reasons the AK is not being recognized: 1) could be a file format compatibility issue. 2) could be a USB hub incompatibility issue as the AK is really 3 drives in USB mode. A possible experiment would be to force format the AK memory cards to FAT but I'm not sure how or if it's possible to do that with the internal storage of the AK. So maybe a moot point.
- Regardless - even if the AK can connect - you won't be taking advantage of the DACs since it just passes the files through USB to the Tesla host. The only way it would make use of the DACs is if it went through an AUX in (which Tesla doesn't physically have). I also find it more convenient to just leave the USB stick connected to the car all the time. It plays the same files as the AK and does a relatively decent job of it. The onboard EQ is not that extensive but it's enough to get a reasonably good sound from your HD music files (much better than XM or TuneIn).
Hope this helps.