Ok... update
got the small box.
Unfortunately the way it is set up, you can only use headphones to monitor either A or B...not simultaneously (Talking about Billy's switch thought!)
The mix output works as intended, but has to be amplified significantly -> headphones would not pull at all.

Ohh well, should of done more reading. Fortunately, I got it for a fraction of the "New" price, so will use it as A/B switch. It is smaller and lighter than my phone, so the good part is, it will not occupy scarce table's real estate.