Comfort and build quality these would not look out of place at £600. Out of all the headphones I have owned / used these have best overall sound which works with every type of music and overall sounds very good, sort of like all the best parts of the HD650, D2000 and HE400 in one headphone but not quite as good as any of them at the parts the do best, but not far off, so a very good all rounder unless you are looking for very bright headphones or don't like bass. Only things I would improve would be slightly deeper bass extension (although it is very good already)better definition in the bass and a slightly more forward midrange .They do not have many reviews or feedback on head-fi, I think these are underrated and more people should buy them.
 
3 Months later : Usually I am bored of headphone or the faults are annoying me by now, I like the 1540 more than when I got them, NAD D1050 + SRH 1540 is overall best sound quality.. no ear fatigue, very comfortable... Sound good with everything!

Not perfect but they do a lot of things very well, probably the best value headphones. Bass and midrange are excellent, treble is too bright and harsh but with EQ it sounds ok.

I think that the old D2000 sounds better than these, they are not bad at the current pricing but they do not sound very natural in the treble and also the midrange is a bit lacking, the size of these beasts is impressive and so is the bass and soundstage, I like the big sound of them, just shame that the treble sounds a bit odd.

Every part of the sound is very good, the bass, midrange and the treble are all excellent, I think that out of all the headphones I have owned, overall these are the best all rounders except the size and soundstage spoils it. It is like Sennheiser was reading my mind when they released these, they have good bas, the usual Sennheiser midrange performance, and also treble which is very neutral and balanced. The overall sound is very good. They are too small and the soundstage is too small. If Sennheiser released a Momentum 2.0 which were about 30% bigger, had slightly better bass and treble and a bigger soundstage, I think that they would be 5 stars.

Comfort is not good at all, bass is pretty good, mids are OK but partially hidden behind the bass and feels like bits are missing due to uneven frequency response, treble sounds very uneven as well with a big spike at 8-12khz with everything else almost inaudible behind this. Overall I do not see what all the fuss is about. They are certainly not bad headphones but they are technically pretty flawed and are not really that good for the amount they cost, it sounds like you are missing a large amount of the sound of the original recording. If they were £100 less then I would say they are very good for the money but at this price, the sound quality and POOR COMFORT does not justify the price tag.

***** DISCLAIMER - Comments in this review are based on the value of the headphones, (I paid £35 for open box pair) they are good for the money and it is all relative to the cost of them compared to other headphones of similar price, compared to more expensive headphones these are obviously not as good.****

Sub bass - Not perfect but good... 

Mid bass - good but not great.

Lower mids - Actually really good I think.

Upper mid - I think this headphone would be  better if 3Khz and up were a bit brighter and more detailed. Still good for the money and fits well with the rest of the sound.

Lower treble -  Some grain and sibilance but not bad, no more sibilance than is present in the recording..

Upper treble -  You can get better headphones for treble for the same money, but these have a good overall sound.

Soundstage - Not huge but ok for a closed / small / portable  headphone, I like the presentation, sounds less hollow than M50 and has a nice 3D effect at times.
 
Overall - Good especially for modern genres such as electronic music etc. Although you could get better if you listen to only metal, rock or classical for example, as an all rounder though... good value if you can get them under about £60.