The ZTE Axon 7's audio

Hello,

So I'm using the Axon 7 for a few days now and I'm really happy with this device so far.
I listen to music quite a lot myself with Spotify Premium (Extreme Quality) and I do believe that the non-rooted stock Axon 7 ROM provides amazing sound already.
On my previous devices I'd have to unlock the bootloader(, disable system write protection), root and install Viper4Android to get similar audio quality.
I guess I could improve the sound quality even more with Viper4Android now but I don't want to mess with my phone and warranty yet.

There seem to be four audio settings this phone can have on the stock ROM without root:
(1) Dolby Atmos
(2) Headset Standard Hi-Fi audio
(3) Headset Super audio
(4) Nothing? Default?

So I'm guessing the audio settings work like this (excluding sound being played from a Bluetooth device because I don't have such device so I don't know):
(a) Is Dolby Atmos enabled?
Yes, phone uses (1).
No, go to (b).
(b) Is the sound being played through the phone's built-in speakers?
Yes, phone uses (4).
No, go to (c).
(c) So sound is being played from the 3,5 mm audio jack. Is Headset Super audio selected in 'Sound and Vibration' in the phone's settings?
Yes, phone uses (3).
No, phone uses (2).

My opinion when using the:
- phone speakers, the audio sounds better with Dolby Atmos disabled. (Maximum volume seems higher with Dolby Atmos disabled too)
- 3,5 mm audio jack, the audio sounds better with Dolby Atmos enabled with speakerboxes/headphones/earphones.
- 3,5 mm audio jack with Dolby Atmos disabled, the audio sounds the same when comparing Super audio with Standard Hi-Fi audio with speakerboxes/headphones/earphones. (Super Audio is much more amplified though)

Maximum volume differences in my opinion (bigger = louder):
With phone's built in speakers: Nothing/Default > Dolby Atmos
With 3,5 mm audio jack in use: Super audio > Dolby Atmos > Standard Hi-Fi audio

So I wonder what the real difference is between Super audio and Standard Hi-Fi audio except for the amplification.
It would be nice if someone who knows about this could explain me :)
It seems that Dolby Atmos doesn't work together with the Super audio/Standard Hi-Fi audio settings.
So you can only use one of the three at a time with a headset for instance where Dolby Atmos overrides the Super audio/Standard Hi-Fi audio setting.
I'd love to see some combination like Dolby Atmos + Super audio purely for the amplification only.

And I wonder how the independant dual Hi-Fi chips work like.
Why 2 chips? Is it 1 for audio output/playing and 1 for audio input/recording?
Or maybe 1 for the right audio output channel and 1 for the the left audio output channel?
Do(es) the chip(s) work for all audio output options?
So do(es) the chip(s) work for the phone's built-in speakers as well as for the 3,5 mm audio jack output?
I know this phone is capable of recording in Hi-Fi quality but is that also true if a microphone is connected through the 3,5 mm audio jack?
I don't know so much about the purpose of the independant dual Hi-Fi chips really...
I guess I'm not really the only one wondering about these things or the only one being interested in these things, so if anyone could clarify it, well that would be great! :D

Thanks in advance!

Cheers,
Abiram26

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