the moded OS takes care of the pro audio circuits, like se/balance, h/l gain, acg. that's why you choosw those options in the SYSTEM menu. 3rd party apps do not need to take care of that.
but IF there is a codec block in the snapdragon soc, 3rd party apps will need onkyo's code/permission to access the sabre dac.
Theoretically this is possible.
However, this is NOT what is happening.
I have tried, in many ways, and along another Head-Fi'er, to explain this.
Any and all apps that route audio to Android will mean that, on that device, it's internal DAC will be used.
Any and all apps that are designed, specifically, to route digital audio to the CPU for modulation will continue to do so regardless of the Android device. Such as Neutron, which is designed, with intent, to BYPASS the hardware DAC for 1st phase digital modulation and use the CPU instead, then use DAC to convert prepared modulation into analogue, and pass to an amp for amplification.
I cannot stress this enough, this has NOTHING to do with Android, Onkyo, LG (LG V10 has an ESS Sabre DAC).
These apps, such as Neutron, should NOT be compared to all other apps that use Android to route audio into a DAC. That is the norm.
As for the System Level functions, which include Volume, Bluetooth, Wifi, etc, Onkyo has made a custom Android OS that has NEW System Level wide functions, AGC, balanced, Line Out, Stand Alone.
These affect EVERY part of Android, including apps, with the EXCEPTION of apps that deliberately bypass Android and DAC to use the CPU to do software digital audio manipulation. For such apps, some System Level functions may or may not work.
Neutron is one big example of an app designed NOT to use the DAC in a first instance.
Please, please contact these app developers for further information and ask if they can modify, or make an alternative, app(s) that will use a DAC first. Or use readily available apps that are not designed to circumvent the norm.
On Sony ZX2, they added a further cool System Level function, global system wide Android EQ. That doesn't exist on Onkyo DP-X1, only in a single app can you access Onkyo's robust EQ featured.
The part about the codec block is also partially true, but in the case of both Pioneer XDP-100R and Onkyo DP-X1, when a 'normal' app sends out to Android a digital audio signal, the modified OS will route this direct to the ESS Sabre DAC(s).
The only time that's not true is with apps such as Neutron.
The LG V10 has an LG Android system but it operates differently; some core, or LG featured apps, will work like Pioneer/Onkyo. However the custom OS is not designed like aforementioned Android DAP's, so some apps may used standard Android kernel to route a digital audio signal somewhere else.
LG are in the right direction but has poorer software implementation than Onkyo/Pioneer.
This is where your points about codec block and Snapdragon apply.