I bought these just over two months ago, and have used them extensively, so I feel now is a good time to review them. I bought these, over other alternatives, after seeing fantastic reviews all over the internet - and although over the months I had spent researching headphones I had swayed to and fro from these headphones - I know I made the best possible purchase.
These were my first pair of expensive headphones I had ever bought, and I am more than pleased with the investment. However, it should be noted that I have used my dad's Bose AE2 headphones on several occasions so I have some experience in this area.
The advantages are endless, amazing sound all the way through the spectrum. I have discovered new parts of songs that I never knew existed and the whole music listening experience is now far more dynamic and enjoyable. The term sound-stage is thrown around a lot, and I never really understood what it was until I bought these as I had never spent more than £15 on earbuds. Sounds comes from all directions, and it is pleasantly noticeable. The bass is thumping and clear - something that a lot of people consider to be the most important aspect of music, personally I like a more balanced experience - but for those who love bass, the bass is there and it is clear and not muddy like with the other popular alternative that I'm sure I don't need to name! Highs and mids are crisp, and instrumentals and vocals sound astonishing and very impressive.
I have listened to a variety of genres of music from pop and rock, all the way to electronic and dubstep and have always been thoroughly impressed.
In terms of hardware, I love the way these look personally, the isolation from the cups is great and they cause no discomfort from clamping, even when I'm wearing glasses as my old, cheap Panasonic headphones did. The cable is thick and durable, and is not wearing out any time soon so far as I'm concerned. They come with a screw on 3.5mm to 6.5mm adapter that is gold plated and very high quality. Also the joint on the cable to the 3.5mm jack is protected by a spring to stop the cable from wearing out - an intelligent and effective design that I was very pleased to see.
There are some disadvantages though, although very minor and won't apply to everyone (including me, but some people may be affected by this). Firstly, they do leak quite considerably at high volumes so not great for use in public, but then again if I am listening to music in public - I'm on the go and opt for earbuds over headphones. Furthermore, due to the amazing reproduction of the sound - low quality MP3s will have every flaw picked out and reproduced. Personally I have begun to upgrade the quality of my music to loss-less as much as possible but this is something that comes with large file sizes and a lot of time burning CDs. Also the cable is long - about 3 metres - which is good for running around the back of a desk, but less so for using straight from an iPod. I have opted to use a Velcro cable tie to reduce the length to maybe 1.5 metres so that it can still reach around my desk, but also work with an iPod. If the length of the cable really concerns you, then go for the standard M50's with the coiled cable. Other than that, they can get a little warm but I can wear these comfortably for ages - the longest I've used at once is probably 2.5 hours, but I could have remained comfortable for even longer than that!
All in all, I cannot praise these enough - they are really amazing value. Although there are some disadvantages, these don't effect me because of the way I use them and the environment which I use them in, and therefore don't stop me from giving these headphones a 5 star review.
I do intend on purchasing a FiiO E9 amplifier and FiiO E7 portable DAC (Digital to Analog Converter) to further improve the experience - but I can happily say that even without these things, they sound great coming straight out of an iPod, phone or computer.
P.S. - It is also worth noting that the only difference between the Audio Technica ATH-M50's and these the M50S's is the cable. These - the M50S's, have a straight, uncoiled cable - hence the S. The M50's have a shorter coiled cable, so if you need that, then buy the M50's. Everything else is identical, so head there for more reviews and then make your choice depending on which cable type you want. Enjoy!