First off, the output of the MacBook Air is more than ample to drive the MOE, however like all onboard audio the sound quality is not that stellar. Even after balancing the MOE using a parametric EQ I do find the treble to be hissy. Adding a good USB DAC/headphone amp like the Asus Xonar U3 or an Audioengine D1 makes all the world of difference; Treble at higher volume levels sounds excellent with great extension and never sounds hissy or thin. Vocals sounds great and never muddy.
I am not too sure about the HTC One, other than the comparative readings on their audio vs the iPhone and Galaxy is quite poor. I use an iPod Touch (5th gen.) and use the Accudio app with the balanced settings for the Momentum as the MOE's smoothed frequency response is 98% identical. It really does make all the world of difference in sound quality. If your HTC One (Android) has an audio player with a parametric EQ, use the below graph to balance the MOE's frequency curve. The black line is the base EQ curve, the red line is what the parametric curve needs to look like in order to flatten the EQ response. The great thing is afterwards you can easily tweak the curve to your desired taste. Hope this helps.