Hello,
I have a Phonitor X. I am very happy with it. I have listened to a variety of headphones with it including the hard to drive Abyss Phi and greatly like what I am hearing (I am not very good with decriptions, but do not perceive it as cold). It has plenty of power. I got the built in DAC version, which I think is the least impressive part of it. I am currently using a iFi iDSD which has a better DAC (in my opinion).
I am using it as a headphone amp and preamp. I very much like that it has 2 inputs, and also a balance (laterality) adjustment, since the way my desk is arranged, I cannot sit centered between the speakers. The crossed function is a nice touch and I use it at times (it takes a way a little bass). In my mind, the crossed implementation on the Chord Hugo 2 is better.
One word of caution. There have been some reports that if you unplug the 6.3 mm headphone plug without muting the amp, it can cause damage. I have not had that happen myself, so I cannot verify it, but I try to mute the amp before unplugging unbalanced headphone cables from the amp.
Hope that helps.