That's it. The Ipod square looks quite off and why my earlier statements. Perhaps it was in an EQ setting etc and missed when tested. None of us are perfect or familiar with every device. I certainly don't think Charles did anything intentional here since there was no need for what he was trying to show. You can see that the Tera rolls a bit in the top from the square and it's confirmed to be -3db down at 20 khz in the actual measurement. I don't feel it's that very important in headphones where it's difficult to know what sounds linear in the highs and since many have a peak up there anyway. People get too caught up in pictures and numbers. Even if you understand them, and I'm sure Charles does better than most, you may pick compromises that are different than others to achieve the result you seek. This is what an undithered 16 bit 1 khz sine wave looks like at 90db down from a similar setup. It's from a HM-602.
There's great debate on how much this matters sonically but 24 bit would 'look' significantly better.
Not the Tera again but here's a 1k sine wave:
The tera will likely look similar but again, the aberrations represent out of band stuff just like those square waves. Folks like their 801s and 602s as well.
It's why I don't think lay folks should use specs as 'proof' of much. Whatever you point to as significant can probably be rebuked by pointing at something else. I've also heard things that look fab on paper that I wouldn't give the time of day. If you like the Tera or an Hm-801 etc, do so because it gives you goosebumps, not because of some silly graphs or because it doesn't need 24 bit to do so.
Edited by goodvibes - 11/28/14 at 7:28pm