There is a lack of info online regarding these cans. There’s a good thread about the ma300 on headfi, the biggest difference in that model that I can see is that the inner padding that angles towards your ear is plusher and sits directly on your ear, in the 100, the driver is angled in the same way but is at a fixed angle, this leaves a bit of room between your ear and the driver which perhaps offers a more spacious/less direct sound stage, but it’s hard to say without direct comparison.
I picked up a set of these for £17 in the HMV closing down sale, there will be tonnes of those available right now, but I have seen them for £11 on eBay. I'll give a brief summary and then elaborate.
In my open, this is a very interesting series of headphones and the ma100 offers the key design approaches at a very low price. The frequency response is excellent and the sound stage is uniquely spacial, feeling very different to nearly all headphones at this price offering an indirect sound which can feel very three dimensional. The bass response is very extended and not 'wooly' like most of its competitors. It is possibly one of the most comfortable phones I have worn with is circumaural padding enclosing your whole ear, and its open design feeling very light and airy, not compressing your ear at all, in a word, breathable. If you desire noise isolation then look elsewhere, but if you like open back designs, you won’t feel lost here. And if you haven’t tried an open headphone, you should. The design is plastic but it has the trademark Sony sturdiness, and it’s actually very subtly understated with its small Sony logo which makes it look like a fairly serious bit of kit. Although don’t expect it to be as heavy or as durable feeling as its slightly more expensive competitors in the Bob Marley Revolution headphone or the new Hesh 2.0 from Skullcandy, in comparison those phones feel like big heavy clamps on your ears, I reveal my bias, but I honestly prefer the ma series with this approach. It is just better ergonomically. One notable thing with this headphone is that it is much quieter than many other headphones; this is on account of its enormous 40mm driver and its open back design. All this really means is that you have to turn the volume up about 20% of where it was, this isn’t a problem for me but it might be for those who need a headphone that has strong isolation and is driving it from a weak device (not a problem for me, my wm-d6c could drive a pink floyd gig.) If you are in that market, you will simply have to spend more money, isolation is a cost to pay but I am happy Sony chose to pay it to produce this lovely, super spacial sound, with a low end frequency response exceeding a grados sr60 and a Beats by Dre (lol) it punches WAY above its weight for this price point.
This design of headphone is very intriguing, a circumaural open-backed headphone with enormous 40mm drivers. Sony have made a lot of trouble with this series to design an exceptionally comfortable headphone. The padding is fabric, that whilst firm manages to distribute itself as an enormous circle right the way around your ear (and I have fairly big ears.) Whilst the top pad is plastic, the headphones are very light and it’s not uncomfortable after long periods. I would almost describe this as a special effect headphone given its unusual sound stage, it is incredibly spacial, stereo sound effects such as those at the end of Alan's Psycadelic Breakfast by Pink Floyd are emphasised to the extreme by this open design. This is such a novelty that I have been relistening to much of my music on these in favour of my Grados. These phones make the layers of any complex instrumentation very easy to define, classical music in particular appears three dimensional, you’ll find yourself feeling as though once instrument is in the other room, the drums behind you, and the vocals quietly being whispered into your ear, this is a very unusual sound stage that I suggest you try for yourself.
Comments on the ma300 seems to apply to this phone as well, for an open can, the bass is extremely extended, possibly more than in any open can I have heard. The treble is nicely expressive and I can happily say that (unlike other cans in this price point) it is not acoustically dampened to reduce the treble distortion in low bit rate mp3 (the Skull Candy Hesh 2.0 is one such phone that does, and it's like someone has turned HX Pro off.)
Like comments on the ma300, during the burn in phase the bass does seem flabby, but as the cone loosens the bass becomes more sharp and punchy. Some have said that they feel as though the midrange seems dampened, and I would say that vocals do feel more 'in the mix' but this is not a major frequency response issue rather a different approach to the sound. There is a mod that has been suggested on another thread that apparently balances the mid range by removing certain 'dampening papers' from around the driver. I might try it, but I am completely content with the overall EQ of this headphone. The easiest way for me to describe it is if you imagine a vocal that in any normal set of phones (and I mean normal, inner ear, supra-aural, whatever.) would sound as though it’s singing directly into your ear, from a base that is fairly close or on your ear. Now if you plugged in the ma100 *and subsequently turned the volume up* the same vocal would seem to be coming at you from a distance, not with any loss in intensity, but with a greater separation from the other instruments, the bass would seem to be coming from your shoulders and the guitar from above and to the left. Sorry if that seems odd but that's what seems to happen when I have compared my grados (and much cheaper cans) to the ma100 whilst listening to Pink Floyd.
I know comparing a headphone in this price range to a Grados is only slightly less extreme than comparing a calculator to Data from star trek but Grados is the go to design for open back phones. Whilst a headphone at this price could never have the stunning definition and tenacity of the Grados it does offer a more extended bass response and its unique separated sound. Perhaps this is created by some sort of acoustic refraction around the aperture of the driver or simply that everything is so big on this headphone, but it is as though you have attached to speakers to your shoulders rather than wearing a headphone.
I am pretty happy with these headphones, I just wish all headphones had cables routed on one side by a jack to jack lead, as this is probably going to lead to me reterminating the cable for these, as it is rather long.
All in I would say that for £17 and cheaper one simply cannot moan, I will definitely be trying to higher rated models if I can.