Firstly, forgive a very likely newb/ naive question.

I am using 300 Ohm headphones, plugged directly into the unit with a USB source.

Setup 1) Using "auto ref level" the system sets to "Lo-Power" and a normal listening level Volume value is -50db or less. That seems a low level (perhaps it is not). I wondered if this would lead to higher noise or any issues. The manual indicates "any level will be fine", but I wanted to at least check here to see if I am configured in a less than optimal way. Loudness indicated it was better/ necessary to use "auto ref level" so I thought this was the "correct" setup.

Setup 2) I had formerly thought that these headphones benefitted from more power. I set the ADI-2 to Hi-Power mod, auto ref off, normal listening levels are similar (volume value of approx ~-45 db). I believe auto ref level was simply using a negative level such that these were similar. Perhaps this is all just adding and subtracting the same thing and there is no difference!

Setup 3) Finally with auto ref level off and hi-power off, normal listening volume seems more like -30db.

Is there any intrinsic difference between these 3 different settings that should matter for optimal performance?  Should I be trying to configure the unit so the volume levels are not so low, or is this just a waste of time/ folly? I am probably / perhaps just moving some addition and subtraction around inside the unit and there may be no real difference.

Any guidance is appreciated. Thank you for your patience.

Tx