Ok it sounds like what you experienced was caused by something completely different than detecting an audible difference between Spotify’s 320 kbps AAC encoding and lossless encoding, encoded over a 256 kbps AAC BT codec, but if you actually want to do a true A/B blind test of 320 kbps vs. lossless on your setup, here’s the place to do it:
Ok it sounds like what you experienced was caused by something completely different than detecting an audible difference between Spotify’s 320 kbps AAC encoding and lossless encoding, encoded over a 256 kbps AAC BT codec, but if you actually want to do a true A/B blind test of 320 kbps vs. lossless on your setup, here’s the place to do it:
https://abx.digitalfeed.net/ (select the first link - “The statistically valid Tidal test to make”)