fiio vs headphone out (on a macbook, or any other laptop) should be VERY noticeable in quality difference. if you are running a dedicated soundcard (creative / asus) there should be marginally no difference in quality, and the only benefit of getting an external amp would be to reduce noise or increase output levels.
anything above a fiio is so marginal i wouldn't recommend going there until you know you have reason. even then, the highest i would recommend going is a dragonfly – amazing little things.
that said, over the years i have used my m902 to run subwoofers, route multiple audio inputs through – digital and analog, do a-b testing with its dual headphone outputs, and generally make me not worry about loss of quality due to hardware, which always bugged me previously.
anything above a fiio is so marginal i wouldn't recommend going there until you know you have reason. even then, the highest i would recommend going is a dragonfly – amazing little things.
that said, over the years i have used my m902 to run subwoofers, route multiple audio inputs through – digital and analog, do a-b testing with its dual headphone outputs, and generally make me not worry about loss of quality due to hardware, which always bugged me previously.