Add an auxiliary audio input for legacy equipment.
Bluetooth is not capable of transmitting high-quality audio. An AUX audio input could be a basic and still very good option to solve this problem – independent of the manufacturer of your audio device.
Moderator: The best choice is still USB with recordings in a lossless format such as FLAC which Tesla supports. This allows full touch screen controls, album art while retaining the highest quality sound. Even from a loss-less source, AUX inputs require extra D/A then A/D conversions which reduces the audio quality.