I have heard both at different times in shops where I live. The Headline sounds better with the bigger power supply. However, I bought a Blue Circle SBH as my SS headphone unit and got it with a really nice preamp installed, for but a little extra. Skylab and I have both posted reviews. PM Skylab if you are interested, to get his opinion on the SBH.
Otherwise, my vote goes to the NAIm + bigger power supply. Very balanced, very detailed, nice extended highs, tight bass, and has the Naim "toe-tappin" sound. I preferred the SBH because it sounded "grander" musically and more transparent - really black background. But again I defer to Skylab.