Pros: Open, airy, balanced sound. Extremely long battery life.
Cons: High frequencies can be resonant.
I initially bought these with a long return rail journey in mind and was expecting to be able to write a review that dealt with their effectiveness on bus/taxi, train and tube (I also had some less than charitable hopes that they might nullify the squeals and shrieks of young nephews and nieces, and the grumblings of aged ancestors). However, nature intervened in the form of extreme weather and the worst flooding here in 250 years so most of my itinerary was submerged/flooded/missing/impassable due to God's wrath at unconventional bedroom gymnastics/global warming/the bloody weather/socialism/immigration/tonyblair/maggiethatcher/bush/obama/notenoughguns/toomanyguns (tip: pick one option, apply to all situations and stick to it, come what may) so instead of trundling by dirty, slow, blocked-toilet train from Sussex to Devon and back via Londonistan I find myself sitting at home hoping for a refund on my rail tickets and using these earphones to defeat the noise of the angry, frustrated motorists queueing at the traffic lights outside my living room window. They (the motorists) can be a mannerless and impatient bunch, prone to gunning their engines, honking their horns, playing truly vile music much too loudly, and occasionally breaking each other's sidelights, mirrors, noses and so on. I am pleased to say that these very cheap Digital Silence branded earphones render most of these goons inaudible. Only the most determined and irredeemably oafish of the knuckleheads manage to make their presence felt and their ghastly spectre is nicely reduced to a tiny fraction of its norm. If I lived in the US I suppose I might buy an assault rifle, several high capacity magazines and the services of an experienced criminal lawyer and then set about radically improving the attitudes and behaviour of passing motorists, drunks, addicts, muggers et al but as I live in England I'll just do my best with some noise cancelling earphones and pass a little time daydreaming some rather gruesome fantasies.
These things hold their charge for a very long time. The manufacturer claims 30 hours of noise reduction. I don't have a sufficiently well developed amphetamine habit to test that claim but I can say that you can definitely go 12 or 18 hours while being happily unaware of external realities and not have to care at all about the battery. I don't have the need or desire to explore beyond this kind of time period so am content. I have absolutely no reason to doubt the 30 hour claim. Charging is really easy, being done via a normal micro USB port, so you can use a wall charger, a PC, laptop, whatever comes to hand. It takes at most two hours to get to a full charge.
The sound is enjoyable and spacious and mostly inoffensive. That may read like faint praise or an expression of indifference but actually it puts these well ahead of many cheap and moderately priced competing products, many of which are sold on their supposed audio quality. I own some very good headphones: Sennheiser Momentum circumaural, Shure SE215, Ultimate Ears SuperFi 5vi and Sennheiser CX95 in ear monitors and some others, and have owned a wide variety of cheap earphones that are sold at prices similar to the Digital Silence's. These DS-101A are not world beating earphones but they are decent and much better than many similarly priced products. They would still be very good value even without the active noise cancelling capability. The bass is not grossly exaggerated, the midrange is nice and the treble is mostly good. The mid range is a tiny bit recessed but that's what you get in just about anything whose price doesn't bring a tear to your eye, so par for the course. The best aspect of the sound is that it doesn't have that closed in feeling that you usually get with IEMs. These are in effect semi open IEMs and they have a very nice combination of the airiness and spaciousness associated with open headphones and the isolation associated with closed headphones. This is a very neat trick and can really grow on you.
I did try these outside while "enjoying" walking in the typical urban environment of busy streets+angry motorists+horrible loud banging "music"+huge trucks, buses etc. and these earphones really can't make all that stuff magically disappear. What they can do is relegate the rumble and intrusive thumping to the background and let you enjoy your sounds, but if you demand utter isolation you may well be better off, depending on fit, with good quality (interpret good quality as meaning "painfully expensive yet just as fragile as cheap junk"), deep seated, noise isolating, in-ear-monitors as made by Shure, Ultimate Ears, Etymotic and so on. Where these Digital Silence noise cancelling earphones score highly is in dealing with that huge urban drone, the big universal hummmmmmm, the steady noise of extractor fans, cooling fans, engines, server rooms, droning bores (present company excepted), domestic appliances, power tools, trains etc etc etc etc ....all that stuff that adds up to ugly, intrusive, inescapable noise all around you, all day, every day. It vanishes. It's lovely. For example when a diesel truck rumbles past it isn't silent but now sounds more like the swoosh of an electric vehicle. A small car going past barely registers. Planes overhead become silent.
If you live somewhere noisy and want something to use at home these earphones are a blessing. These offer much better noise reduction than a pair of closed circumaural headphones (for example my Momentums) and are much easier to wear for long periods than IEMs that go deep into the ear canal. If you wear them with the cable looped back over the ear they are snug enough that you can easily sleep with them in.
The sound quality is definitely not perfect but the feeling of openness is very appealing indeed. Higher notes can sometimes sound a bit hollow or resonant so I guess if someone actually measured these they would identify some ringing and perhaps some uneven response at higher frequencies. The midrange is decent so voices mostly sound very natural. You get the benefit of larger drivers than are usually found in IEMs (13mm in these) and these don't sound congested or muddled like most similarly priced but smaller IEMs. Fit is fine. Probably the best way to wear them is cable to the front but looped back over the ears. This eliminates cable noise but leaves the controls accessible.
There is a tiny bit of hiss when you switch on the noise cancellation but it really is minimal and not something that will distract you in quiet passages of music. I was impressed enough by these that I subsequently bought the top of the range model, the DS-421D (a review will follow after a week or two of use). The more expensive model hisses quite obviously but is a better earphone in most other repects but so it should be - it costs three or four times as much. This budget model, the DS-101A, is actually outstanding value and a genuine bargain. If the power runs down (do you stay awake for 30 hours???) you can still use it as a normal IEM and it is not bad (though it has almost no isolating property without the powered circuit). I've only had it about three weeks so can't comment on durability but the construction seems OK - the cables are of decent thickness with good strain relief at every join and there is nothing that invites concern.
I wouldn't want these as my only IEM but they are cheap enough to be a really worthwhile option and also a great way to try out noise cancellation without worrying too much about the cost.