When doing so, make sure to look at all the preference options. If you're looking for clarity on this issue, try the different services and decide for yourself. create a high quality 256kbps AAC with (slow) highest quality encodings of the best source, the end result may subjectively differ based on preferences on EQ, source, etc.

However, it's possible for another service to have better sources and thus through the process deliver something better. in theory, at least objectively via the process. In my experience, Apple has great sources and has great encodings of those sources, so Apple Music is going to deliver the best, or at least match any other service. So to that end, considering re-encoding and transcoding degrade the quality, what you want is the best quality encodings of 256kbps AAC (not all encodings are equal and neither are their sources). If it's an analog source, it will be converted to 256kbps AAC with the analog to Lightning cable. Yes, it has hi-res lossless and spatial audio albums at no extra charge, though Apple isn't. If it's a higher digital source, it will be downconverter to 256kbps AAC before streaming over Bluetooth. Apple Music runs second to Spotify in terms of subscribers, but surpasses its rival in one key respect. What a lot of people are missing is that whatever the source is, by the time it hits the APM, the best quality file/stream is going to be 256kbps AAC.

Spotify vs apple music audio quality