Research and investigations conducted by Audio Community demonstrates that Apple’s implementation of AAC on iPhones are actually so good that 256 Kbps AAC files seem as transparent, detailed and noise free as 990 Kbps audio transmission offered by Sony’s LDAC on Android phones. You guys can actually see it for yourself that THD+N and TD+N both are incomparable to AAC implementation on Android phones and how do they stack up against LDAC.
It doesn’t matter whether the playing audio file is in AAC format or not. What we’re arguing here is AAC transmitting bluetooth codec not an audio file encoded and decoded in AAC format. AAC bluetooth codec is different than AAC audio files. Whatever file type you play on iPhones whether MP3, AAC, ALAC, MQA,… will eventually be transmitted through AAC bluetooth codec/ Encoded and Decoded. I hope this clarifies what you’re trying to figure out.