You could transfer all of your multichannel tunes (from SACD, Blu-ray, DVD-A, DVD-V, DTS-CD discs, whatever) to an SD card or USB stick as FLAC files. You could optionally copy them to the internal jukebox, but that is limited to 9.9 GB (I store my Audi's baby pictures and videos there). Convert your SACD DSD to 88.2 kHz PCM (best result in the Audi IMHO). The largest SDXC card I'm using for playback in my 2018 A4 allroad can hold 1TB. I've been listening to quad, 5.1 and 7.1 tunes -- I haven't yet checked for 7.1 channels in the sedan models. And remember to turn off the Surround effect!