Hi, I am wondering which would give a better performance for my HD600. The O2 amp or a fiio e9+e7.
Uhm... if you're just gonna get the O2 amp then you're pretty much going to be using the DAC from your Macbook. The E7 + E9 combo would easily be much better then, since the E7 > Macbook.
Amp wise alone, the O2 is cleaner and has a lower output impedance.