cx-30 audio sound 5.1 not surround

I have just acquired this magnificent vehicle, I am very happy with it.
However, I would blame the lack of information in the manual about GPS and
also for using the audio system.
I did not find any information on the usb key to use to store music.
After many tests, I understood that it was necessary to format the key in fat 32.
I have successfully formatted a 256GB key, but haven't gone beyond that yet.
Is it possible to use a 1TB hard drive?
The music reproduction is indeed of high quality.
The big criticism I make is that I can't play recorded music
in multi-channel sound.
It plays multichannel flac files but transforms them into stereo.
Can we connect a cd player and SACD or blueray via the usb terminal and switch to multichannel SACDs?
I can't find any info on this on the internet.
When I talk about its multichannel sound, I'm not talking about its transformed by a DSP as it is
the case in this car, but of recording which can for example restore
different instruments in each speaker.
I have a jvc exad kd-avx2 which does that without problem.
I noticed that we could play a movie in mp4, but for reasons
only when stopped.


Reflection of Elegance
'20 Blue CX-30
I know for sure Japanese models actually come with a CD/DVD player built in. Also, their interior is actually a bit different than ours in the US. I am uncertain if you could connect a portable CD/DVD via USB and be detected, but chances are that it will not work.

As far as movies only playing while stopped, that is likely for reasons of safety. I assume this goes with Mazda's plan of creating less distractions. It makes sense with the infotainment in the 3 and CX-30, among other things.