I wasn't answering the original post, I was posting about my solution for videos with low volume and using a versatile mixer instead of a one trick pony headphone amplifier.
I got the impression that you did seem to be also making the suggestion that anyone who was thinking of getting a headphone amp should consider getting a mixer instead (for versatility).
The reason I made the comment is that Chris said he is still thinking of getting a headphone amp, and in fact also made it clear that he was at least considering
getting your Mackie. Recall that Chris was thinking of getting new headphones and/or a new headphone amp. (presumably to improve the sound). I'm simply cautioning that your Mackie may not be the best choice for Chris' situation. The sound is already loud enough, and I'm presuming that a premium instrument such as the N2 has a pretty good headphone amp in general(?), so just maybe a "one trick pony" is the most appropriate thing to get. I could well be placing too much importance on the output impedance, though. I won't be surprised if you don't perceive any degradation in fidelity when you do hook up the Mackie. (I will be a bit surprised if you notice any improvement though - of course I know that's not why you are buying it)
Just btw, there has been one (only one) occasion in the past where I recommended a low impedance headphone amp, and the person did actually notice an improvement. They were reasonably thorough in isolating the output impedance as the reason for the improvement, too. http://www.forum-pianoteq.com/viewtopic.php?id=2174
Chris: if you were to get active monitors (speakers with inbuilt amplification) you probably won't need to amplify your N2, especially if you take care to get monitors that can accept low level ("consumer") line inputs. One thing I learnt recently (in this forum) is that it is
possible for even active monitors to be not loud enough, because the line level inputs on some speakers are designed mainly for professional grade levels, which are higher. This came as a great surprise to me.