[toast0]

I'd guess AAC is technically possible, but not actually supported. A list of formats from a random current receiver is:

2-channel Linear PCM: 2-channel, 32 kHz – 192 kHz, 16/20/24 bit

Multi-channel Linear PCM : 7.1-channel, 32 kHz – 192 kHz, 16/20/24 bit

Bitstream: Dolby Digital / DTS / Dolby Atmos / Dolby TrueHD / Dolby Digital Plus / DTS:X / DTS-HD Master Audio / DTS-HD High Resolution Audio / DTS Express

I'd imagine whatever source is getting AAC is going to need to decode it and send as linear PCM, which should be fine.

[piperswe]

In my experience multi-channel AAC gets sent as multi-channel LPCM over HDMI, whether that be eARC or not. That's fine though, I don't really care what part of the chain does the AAC decoding because it has to be turned into LPCM _somewhere_.