De-Emp and Direct Which to Use

On my DAC, there are two outputs set: De-Emp and Direct. Which I should use? and What is the pro/con of each. Thank you for any advise.
Which DAC are you using?
What brand of DAC? On ours we usually use direct.
Most DACs switch automatically from regular to DE-EMP if the cd was recorded with EMP! If you switch in the DE-EMP with regular CDs, you will be rolling off the HF.
It is the Audio Note DAC1.1X
I used "Direct" because I don't what "DE-EMP" does; hence this thread. On the back of AN DAC1.1X there is a push button to select the output - Direct/De-emp.
Again: You use DE-EMP with pre-emphasized CDs. I do not know the AN DAC but most DACs switch automatically and most of those have an LED indicator informing the user that this has happened. If the AN requires you to make this decision, the problem is that pre-emphasized CDs are rarely so labeled. Seems like a dumb system. Why not ask AN or consult the instructions for the DAC?
You use direct on Audio Note DAC's.
Then what's the other for?
Dear All,

The facility for a manual de-emphasis was borne out of the need to be able to allow de-emphasis on discs where there is no encoding that triggers the automatic de-emphasis.

Now you may ask, are there such CDs??

Unfortunately yes there are and quite a few (not that the record companies would admit to it off course) I have a number of Jazz and a few classical CDs all of which sound clearly pre-emphasized, but none of them trigger the auto pre-emphasis, so the manual version is pretty useful.

For normal CDs always use the direct out.

Peter Qvortrup