@Leandrusi,
If it helps, with this interface I think you can only direct monitor the inputs as mono. The only possibility to stereo monitor is through the DAW. If you check out the Scarlett 2i4 you will see it has a little switch in the front panel (Mono - Stereo), that means this other interface has the stereo monitoring function. As I can deduct, this surely means the 2i2 doesn't have this function.
I imagine they do this for the following reason:
Imagine that you are recording two different instruments - each one with one channel (for example, a microphone and a guitar). If the direct monitoring is stereo by default, the user would mandatorily hear the microphone in his left ear, and the guitar in his right ear, or left and right speakers in that case. In the case of speakers this can become a bigger problem if the output is to a mono speaker system, as is my case.
As this is an economic interface, I'd say they decided not to implement the physical switch in order to reduce costs. This led them to decide whether doing stereo or mono by default. I think they did that more like a compatibility feature, trying to be effective at most situations.
I was looking for information about this feature of this interface (I'm considering buying it), and finally stepped by here, and I decided to share it in case that can help you or any others. Hope it helps.

bposfaci