Work around. 1. root phone. 2. Plug a 3.5mm M-F extension cable of your choice into the phone, plug in a 75ohm or greater impedance adapter into the phone, start music app, unplug adapter and plug in your headphones. Will stay in high mode as long as extension is plugged in.
Ah.. but rooting voids warranty and using a 75 Ohm series resistance in series with a much lower impedance headphone drops the output power again due to voltage division + most low impedance headphones alter their tonal balance so also does not seem like a viable workoraund.
Acc. to Amir it puts out 1.7V (= 30mW into 100 Ohm) in high voltage mode. Using 75 + 32 Ohm = 107 Ohm means a 32 Ohm headphone receives 0.51V =8mW.
Granted this is almost 3.5dB more and audible but not all headphones can make use of it because of the now created very high output resistance.
I think any audiophile that is limited to using a phone like this probably still needs an external amp for both low and high impedance headphones, perhaps with the exception of efficient IEM's.
What I find weird is that Shanling uses just one of the same chips and gets more power out of it than 4 in parallel.
A strange decision from LG, possibly inspired by the desire to create only low power devices to protect the hearing of people.
When rooting the phone does this mean it becomes possible to force the DAC chips to let the amp part switch to low voltage mode which increases output power for low impedance headphones but limits the power for high impedance headphones. Does this mode have to be selected manually or can it do it autmatically and is just disabled by LG ?