Edit: D'oh! Typo in the title but I can't seem to edit it. It should be "How important is distortion *in* choosing headphones?"
I'm getting close to buying my first set of "real" headphones. I'm coming from the speaker world where I've dabbled in designing speakers. If I were to give the top priorities in designing an excellent speaker I might say, roughly, in this order:
1. flat frequency response
2. low distortion drivers
3. good phase matchup between drivers
4. flat impedance plot
Get all these things right and you will have a speaker that really sings. Most headphones seem to only have a single driver (is that correct?) and the impedance plots are relatively flat. So forget points 3 and 4. That leaves us with only the flat frequency response and low distortion to worry about. If the frequency response isn't close to flat, things will sound funny.
For distortion, I've been looking at all the excellent data provided at headphone.com. Let's compare some popular choices... the Apple stock ear buds show tons of distortion. The Grado SR60i's are much better, but still notable distortion above 500 Hz. The AKG K701 is lower still in distortion. Looking around at all the full sized cans below about $500, one of the low distortion champs seems to be the Beyerdynamic DT770 32 ohm.
The DT770-32's are well liked, but as far as I can tell, not nearly as much as other cans with more distortion. Interesting. I realize that some people enjoy even order distortion (e.g., tube amps) and odd order distortion can be jarring.
Factoring in flat frequency response, low distortion, my best guess at comfort, price, and general opinions here at head-fi, I'm leaning toward the standard 250 ohm version of the Beyerdynamic DT880's. So let's look at the distortion of the various DT880 options. Near as I can tell, people here seem to prefer the 600 ohm flavor over the 250 ohm, and then the 32 ohm least. Look at the distortion plots. The 600 ohm looks worst, by a fair margin. Worse than the much cheaper Grado SR60's. The 32 ohm might have the least distortion but it's a close call with the 250 ohms.
For speakers. distortion 35 db down from the fundamental can still be heard, I find. It's not a huge deal but it'll sound better if you can eliminate it. I'm wondering how far down headphone distortion doesn't matter anymore. Will the Grado noise at -90 db matter or you'll never know it's there?
Just trying to start an discussion that might be interesting and help me pick which headphone to get. Thanks!
Edited by DrJon - 9/4/11 at 10:55am