Anyhooooo, I have diched my external headphone amps for a few days to see what the M-Dac's headphone amp section is capable of. I am amazed by the M-Dac in every sense.....
Feeding via RCA output to HifiMan EF-5 (capable of driving almost any phone) - Great with my HE-6 and LCD-2
Feeding via balanced XLR's>Hirose into iBasso PB-2 - Great with ES5's and LCD-2
On board Headphone amp - Great synergy with LCD-2!!
All of the above is based upon ipod classic (Lossless) > CLAS > M-Dac
With the exception of the LCD-2 the M-Dac is the best money I spent in 2011!