It has a “line out” mode, not a true line-out.
And this line-out “mode” doesn’t bypass the amplifiers, there’s no separate audio path, it just sets the output level to a fixed 2V. So any evaluation will always be influenced by the performance of the amp, not just the DAC.
The “line out” toggle in the notification bar/settings drop-down doesn’t do quite what you’d think even then, either. It doesn’t directly put the unit in line out “mode”, it simply turns the option to do so on or off.
Once you turn that setting on from the notification bar, you then go to the volume control screen and now you’ll see a new “Line Out” button in the middle of the screen (the volume function with variable output is still enabled at this point). To get line-out “mode”, you have to press that button, at which point you get a warning/confirmation of what its going to do, and then it goes into “line out” mode - the screen will show that mode, the 2V output, and the volume indicator in the notification bar now just says “Fix”
This also disables the volume control - using it just brings you back to the volume screen - where you can turn off line out “mode” off again if you wish.