Is there a better way to visualize harmonics than a single frequency?
Distortion levels are frequency and above all amplitude (level) dependent.
One also needs to take audibility levels and actual listening levels using music into account.
The difficulty with measuring is background noise. That's why on Tyll's plots 90 dB is worse than 100dB where in reality 90dB will be better but only appears to be worse.
To get down really low you need a completely dead room, both in reflections as well as background noises which for the lowest frequencies is extremely difficult. Otherwise it becomes just 'an indicator' for gross errors (which in my book is fine).
So it helps if distortion levels are measured at different SPL (realistic ones) and over the entire band (depends on the harmonics as well)
This means perhaps FFT at various frequencies and amplitudes (that means a LOT of measurements and heaps of plots and posting them).
Too bad if you have one at 5kHz for instance where it happens to be really bad but excellent at 4.5 and 5.5kHz for instance and almost inaudible with music.
The 40Hz at 100dB SPL will end really really bad for most dynamic headphones yet may sound totally fine at 90dB average SPL levels (is really loud already) with music peaking at 100dB SPL.
The review from Amir is a quick one with FR (as it happens to be for that particular rig only) acc. to a standard where the SINAD number will be no measure for quality with a different distortion measurement and Amir's short subjective opinion.
Based on that property alone the LCD-X would get the highest recommendation and be top of the list warranting another panther.
The FR plot is really only readable for most initiated people who can 'translate' the curve + target in their heads to estimate FR. so would expect the 'corrected' version as well for the folks that have a hard time correlating (includes me) to actual sound.
With EQ you can 'fix' a lot of headphones and improve others. It is essentially needed for almost all headphones.
It doesn't look like the HP measurements will be a 'one stop shop' type of thing just like it isn't on all other websites. These too only have scattered info someone might be looking for. Rtings also adds info, crinacle adds info, oratory adds info even RAA adds other info.
I see Amir's review as an addition of the info that is already available. A second opinion, another few reference points to a giant puzzle as it were.
Just made with other equipment and another copy of an already measured headphone elsewhere.
It can add info or confirmation of what's already known. If that's what Amir is after then that's O.K.
At this moment it is nowhere near the Klippel measurements and far removed from the DAC and amp measurements.
Amir is just starting this so give him some slack and pointers to fine tune his thing and am interested to see how this evolves and what the standard 'reporting' will be and how this will add info to what's already out there.
Just measuring and reporting FR on one particular test rig isn't all the info that is needed. The most important factor... yes. But not the only one.