hey bareyb,
I totaly understand everything you have posted, I just don't understand your primordial wish: MORE power.
You are misleading yourself much, power is Not everything headphones need, I will take lower but cleaner power output Anyday compared to 4 times more power but less refined, less airy.
Power is not all what your headphones need, all that specs is nothing, you headphones will not use more than 200-300mW anyway, at 1W output your headphones will became speakers (i'm not joking).
And btw: In my opinion Benchmark DAC's are brightest and most un-natural DACs I have heard in my life. Grace is much better regarding natural, real, palpable sound - again IMO.