[pifidelity]

  Could you check your essence with a 600 ohm headphone?
.

 
Unfortunately I don't have a pair of 600ohm headphones to use, though the 600ohm load resistor I used should've replicated this - you'll get about 60mW max out of this card into your headphones.

 

[Emir]

do you have any 250 ohm to try them out?

 

[pifidelity]

  do you have any 250 ohm to try them out?

 
No sorry, my headphone collections pretty limited! Highest I have are my AKG K712 (60ohms)...
 
You should be confident with the measurements though, I know it might be hard to imagine how loud the numbers really translates into but, according to your headphone specs (600ohm, 96dB/mW), the essense ST outputting 60mW into 600ohms should be sufficient. 
 
If you're still weary, I'd go with cel4145's advice and get external DAC/amp with a cheapish soundcard for the dolby virtual surround. The Schiit Magni2 for example can output 130mW into 600ohms, which is more than double of the essense ST.

 

[Emir]

Ok thanks

 

[PurpleAngel]

  And the other questions?
 
"I can spend up to 200-300 bucks, so the ZxR is affordable. Could it drive the the 600ohm Beyer?
Also, I could exchange the 600 ohm version for a 250 ohm one. Should I do it? Do they have similar sound?
I use headphones mainly for watching movies, so a clear dialogue is important"

 
My $60 FiiO E11 can (just barely) drive 600-Ohm headphones, at max volume settings.
So I think it's better to find a amplifier that can drive 600-Ohm and do it well.
So maybe read up and ask on this thread about what to get to drive 600-Ohm and drives them well.
http://www.head-fi.org/t/429371/the-beyerdynamic-dt880-discussion-thread
 
I think you should get something to provide a DAC function (sound card or USB DAC) for around $50-$60 and spend all the rest of your audio budget for an external headphone amplifier.
 
Or maybe get the SB-ZxR and try it with the DT880 600-Ohm, it does not work well, then swap the 600-Ohm for the 250-Ohm version of the DT880.
The 250-Ohm and 600-Ohm are fairly close in audio quality (I own both).

 

[Emir]

In your opinion is the 250 ohm beyer good for movies? Are the 250 ohm and 600 ohm ones similar in this regard?

 

[PurpleAngel]

  In your opinion is the 250 Ohm Beyer good for movies? Are the 250 Ohm and 600 Ohm ones similar in this regard?

 
The DT880 (250/600) are a little on the bright side, but otherwise good for listening to any type of audio (movies, music, gaming, etc).

 

[Emir]

is the 600 ohm version better than the 250 one for movies?

 

[PurpleAngel]

  is the 600 ohm version better than the 250 one for movies?

 
I'm guessing not much of a noticeable difference for movies.

 

[Emir]

Ok thanks  I'll go for the beyer 250 ohm + ZrX since it will be driveable that way.