What are the point of the LODs? Is there any difference vs the audio jack?
I'm talking about something like the FiiO L9, L11, etc.
Without an LOD, both the device and external device amplifies the signal rather than just one, leading to higher noise and bad sound quality.
The volume on the device will show as maximum. You can then control the output volume on the external device.
For certain devices like the Fiio, you can then tweak the sounds with EQ. It will sound terrible with EQ if your signal is double amplified then tweaked.