Shure SRH 940

These headphones are a perennial source of frustration for me. They sound fantastic for closed headphones at their price. I'm a big fan of neutral and detailed cans with a fairly flat sound signature, and these definitely deliver. Highs are crisp without being at all harsh, mids are clear and detailed, bass is well balanced and controlled. Sound wise, these are probably my favourite closed headphones of the ones I've owned/trailed (DT250, DT770, M50x).

Build wise, these are my least favourite. They are made out of brittle plastic, which doesn't seem very durable. The plastic is also quite noisy, especially around the joints between the cups and headband, and the headphones creak if you move your head much at all. I've had mine for a couple of years and used them pretty heavily, and the creaking has gotten worse over time. It is particularly audible when listening at low volumes. The headband presses down on the top of your scalp and becomes uncomfortable after a while. The headband material also degrades with time, and there doesn't seem to be an easy way to replace it.

I think these could be truly excellent cans if Shure had done a better job with build quality.

The name Shure alone stands for its long time professional heritage and live components. So I was intrigued before listening. 
 
I listened to at least 5 different music tracks and three different sources (including my usual jds headphone amp).
I got consistent impressions this is a not in your face type of headphone. While it convey the sounds in a non offensive neutral manner, I can't say it is accurate in terms of dynamics in the lows or high registers.
When connected to a Pioneer amp, it became evidently a bit harsh in the high register.
 
The built quality seemed decent but for the asking price, I think the SRH940 could have done better.

These headphones should be valued for providing an ultra-bright sound signature not offered by any other headphone that I'm aware of.

Comparisons with the HD800: If you compare the 30hz and 300hz square wave measurements from the innerfidelity charts between these and the Sennheiser HD800, you'll see that the two are almost identical. I own the HD800s and this, and I can say that the SRH940s are much much closer to the HD800s than their prices would suggest. The HD800s handle bass and mids better, and their treble is a little smoother, and they have better spatial characteristics, but the two are close, with the SRH940 being brighter.

More on their brightness: These are possibly the brightest headphones made today, which is something I appreciate. They are almost like taking the tweeter out of your stereo speakers and putting them up to your ears. OK that's an exaggeration but do not underestimate how bright these are. On their bass output, they're not like a clock radio that can't put out bass. If you play a bass heavy song you'll hear the bass notes and they can go quite deep on the frequency chart. But if you like to hear a bunch of bass on all your songs, then you'll need to use the equalizer to turn these into the headphones you want.

Ultimately, if you want to know what your music sounds like with excess exaggerated treble (and sometimes it sounds better) these are the headphones to own.

The only problem is that they put pressure on one spot on the top of my head if I wear them for a long time (the cushions were designed poorly and they focus the weight on one spot).