Actually, I think the Benchmark's headphone jack is excellent. You can also get a headphone jack mod done at Empirical audio along with other mods.
Where are you using the headphones? If it's next to your two channel setup why not go from your computer into the Emm dac via a usb converter and then connect a great headphone amp? In other words, why are you choosing another dac with the headphone amp as opposed to the headphone amp only?
I've gone through my headphone phase and found that the Stax amps/cans are my favorite so if you buy something like the Headroom you'll be 'stuck' with using dynamic headphones. Make sure you prefer dynamic cans over electrostats first.
Where are you using the headphones? If it's next to your two channel setup why not go from your computer into the Emm dac via a usb converter and then connect a great headphone amp? In other words, why are you choosing another dac with the headphone amp as opposed to the headphone amp only?
I've gone through my headphone phase and found that the Stax amps/cans are my favorite so if you buy something like the Headroom you'll be 'stuck' with using dynamic headphones. Make sure you prefer dynamic cans over electrostats first.