[RexAeterna]

Not once have I gotten used to a pair of headphones.  If it bothers me from the get go, it's only going to get worse as I get to know the phones better.  But rarely does my opinion change much from my first 5 minute impression unless my tastes evolve over the years (they haven't that much) or I use different equipment.  I don't get how someone can "unhear" glaring issues with the upper midrange or treble.  That doesn't sound healthy to me. 

As for unfatiguing, from cheapest to most expensive

AKG K240 Sextett, HD650, LCD-2, Stax 007

Haven't heard the HE500 except for a few minutes at a meet and it was noisy so I won't say but it didn't seem as fatiguing as most.  If you like the PK1 I bet you'll like the HE500. 

same here. 5-10 minutes is all i need to know if the headphone or speaker is good for me,listening for hours won't change my mind. i'm sorry to tell people but if your forcing yourself to get use to very bright emphasized fatiguing treble,all you doing is damaging your hearing.

 

[daveDerek]

it's pretty amazing that no one has mentioned the sony r10 so far, so i will. it's also very comfy.

 

[kingpage]

I was gonna say "a headphone with no treble", until I saw the word high-end.

 

[Beagle]

Quote:

Quote:

Your post was really fatiguing.
 

But you read it anyway...
 

 

[kingpage]

LOL like any audiophile, he would listen to the music anyway despite the fatigue.

 

[Pingfloid]

[size=medium]The HD650 has received many votes, but the result may depend on the rest of the gear and ears.[/size]
 
[size=medium]In my personal experience with the HD-650:[/size]
 
[size=medium]HD-650 + RME Fireface 400              Boring. Fatiguing. Clinical. Not enjoyable[/size]
[size=medium]HD-650 + Creek Audio OBH-21        Similar as above.[/size]
[size=medium]HD-650 + EMU 1820M                      Similar as above[/size]
[size=medium]HD-650 + La Figaro 332C                  Better than above. Enjoyable for short listening periods, but high frequencies a bit harsh.[/size]
[size=medium]HD-650 + DIY 300B SE                     Sweet and warm, but ultra-fatiguing PITA because of hum noise.[/size]
[size=medium]HD-650 + Practical Devices XM6        Not much fatiguing. I can use it for quite long listening periods.[/size]
[size=medium]HD-650 + Sense G3                            Sweet, warm, and non-fatiguing.[/size]
 
[size=medium]Of course, all the above may completely differ if you use other ears and brain than mine.

[/size]

 

[Dubstep Girl]

LCD-2, but the fatigue won't come from the highs, but rather from their weight. 
 
HD 650s are the least fatiguing for me.

 

[Audiowood]

In order from most less fatigue HD650, LCD-2, LCD-3.
 
As agreed with above post LCd-2 & 3 will get you head fatigue, wearing them is like putting on a hard hat... amazing clamp force left & right and gravity force from up and down.

 

[Dubstep Girl]

hard hats are more comfortable than the lcd-2, i can deal with wearing one a whole 12 hour shift. lcd-2, probably not.

 

[ardilla]

As the OP, I can now summarize my experiences. 
 
1) Fatigue is subjective
2) Source matters
3) Brightness isn't the only source of fatigue, but sure is a very good indicator. 
 
Here's my fatigue ranking of the High end phones I've spent some time with. Obiviously I didn't have them all at hand to compare readily - this is by mamory and purely subjective. I owned all except the 007 which I only had on a short term loan.  Ranking is from least to most
 
1) Yuin PK1 earbuds on WA2 amplifier (!!!) Earbuds that sound like great full sized open cans. Totally non-fatiguing, clear. Really needs a good amp, shines with the WA2
 
2) HD650
 
3) HiFiman HE-500
 
3) Fostex T50RP
 
4) LCD-2
 
5) Stax 007 mki
 
7) Beyer T1
 
9) Senn HD800 
 
 
 
Further, all Gado's I've heard I find more fatigiung due to brightness than all above.
 
Of the Stax flagship, the 007mk1 is the least fatiguing, the 007mkII just a tad brighter, the 009 is much brighter. 
 

 

[superliu]

HD650 sounds extremely natural and of course,not fatiguing, but hd650 doesn't quite fit on my head and my ears get hurts after around 2 hours of music. beyer's dt880 990 make me feel nothing even after 10 hours of listening (yes, I did that before). However the headband became sticky after 200 hours of usage and is driven me mad.. The sound of 990 is a bit too overwhelmed for me so I vote for dt880, which I only listened a few times and did not have the oppurtunity to own one.K701 Definitly sounds natural with less bass but the headband's design is weird and I can feel the strong pressure from the headband.

 

[ardilla]

Wrap some tennis(or bike handle-) bar grip tape to wrap around your headband   These tape's are made for long term sweaty but comfortable skin contact. It will also vastly improve the sound because the headphones will resonate better with your head. 
 

 
Instruction video
http://www.youtube.com/watch?v=yn1cYRF5tJc
Quote:

HD650 sounds extremely natural and of course,not fatiguing, but hd650 doesn't quite fit on my head and my ears get hurts after around 2 hours of music. beyer's dt880 990 make me feel nothing even after 10 hours of listening (yes, I did that before). However the headband became sticky after 200 hours of usage and is driven me mad.. The sound of 990 is a bit too overwhelmed for me so I vote for dt880, which I only listened a few times and did not have the oppurtunity to own one.K701 Definitly sounds natural with less bass but the headband's design is weird and I can feel the strong pressure from the headband.