We have this from time to time: a confused user who didn't get it right in the beginning drives himself into total chaos by continuing the wrong routes. Let's see if we can detangle this. But it won't be easy as long as you don't use precise descriptions of what you want to achieve. Saying out 1/2 is dead when you want to monitor the analog input is a statement that will steer us in the wrong direction as well.
First of all: a total reset of the unit is described on page 11 and page 29 of the current manual (version 2.4). Please use the online version:
https://archiv.rme-audio.de/download/adi2profs_e.pdf
A PDF is searchable! Open it, Ctrl-F, type in 'Reset' and there you are - page 11.
You might also want to update the unit to the latest firmware to make sure you don't run into an already fixed bug while exploring the unit:
https://www.forum.rme-audio.de/viewtopic.php?id=28936
Fiddling around with all knobs trying to find out what they do: we added a simple and easy to understand folded paper that explains all this and a bit more for quick starters that don't like to read the manual. Of course that paper can't explain everything.
The unit comes in a default configuration for typical first time use. That may not be your personal application, so needs some tweaking then. For example when plugging in Phones 3/4 outputs 1/2 in the rear are muted. You can disable that in the dedicated Phones menu (which you might not have if the firmware is older), but you can also use the long press on the VOL button to change between front and rear (Toggle Phones option). That's quite easy if you do one thing straight after the other.
A peak level of -1.7 dBFS @ 4 dBu will give -4.7 dBFS when set to +13 dBu with +6 dB Trim Gain (simple calculation: 9 dB minus 6 dB = 3 dB difference). You also have to note that the ADC is extremely noise free. Especially with vinyl as input you could record at -40 dBFS peak level and won't notice a difference in recording quality. What you have to do (and that is always true) is to normalize an analog recording after it is finished - the current record level/volume doesn't matter. Better lower with no peaks clipped than too hot. The software that you use will have this feature.
So please reset the unit and let's start over again with one question after the other.
One tip upfront: the unit comes with a Basic mode called DAC, which might help you using it as that simplifies input control and clock setting. See page 40. How to set this? See page 34, Chapter 17.1, second paragraph.
We also DO have support by email and telephone. If you are in the US our product specialist Jeff at Synthax US will be happy to help you with your setup.
Regards
Matthias Carstens
RME