I am an amateur recording engineer that mainly uses a laptop pc on location with a Focusrite Scarlett 18i20.
The bus power is no doubt as noisy as a baby with a full diaper that's up way past bedtime.
I use the same interface at home with monitors, etc. but I had a HUGE problem with the interface dropping out every 15 or so minutes with low latency settings in my ASIO driver selected.
Long story short, this goes in the middle with stock cables (or 3 dollar ones from the local PC guy) and all my problems disappear. Hours and days connected on end with no drop outs.
The only annoying thing would be the wall wart which is mainly a portability issue for me.
 
I now have two, one fixed at home and another in a padded camera bag which goes with the rest of my kit.
 
I won't say it makes my recordings sound better or anything, because I haven't done comparisons, but all I know is that it lets me do what I want.

Here are my very brief impressions after listening to this earphone for approximately 12 hours without burn in. Very early stages, I know.
Sampling artists I used include John Mayer, Katharine McPhee, Brooke Fraser, Kina Grannis.
Currently owned in-ears: Shure SE215 (3 years), Sennheiser IE8 (2 years), Logitech UE600 (2 years)
 
I purchased these in-ears as I had an increasing need for a neutral sounding set of ears which I can pair with a monitoring pack while positioning microphones for live gigs.
 
 
This in-earphone will definitely not wow at first listen.
But they will provide endless insight into the music.
 
 
Comfort:
My ears are extremely picky with silicone tips and I couldn't get anything other than the foam tips to sit comfortably.
 
Sound stage:
The strength of this earphone in this area is definitely contributed by the lack of any emphasis in area. You'll notice that this is generally what I'm going to say in every frequency region.
There's nothing in the sound that adds to the dynamics of a song and brings those instruments in and makes them more audibly present. This helps with both separation and space.
Layers of instruments aren't blended together even with similar frequency signatures. Orchestral sections are so well separated and placed that it makes conducting seem like an easy task to do blindfolded.
 
Lows: (Sub-bass to 200Hz)
Deep and extensive. Not immersive.
John Mayer's 'Belief' and 'Slow Dancing In A Burning Room' 
There is no 60-80Hz punch like the Shures, or mid bass hump that veils the mids (IE8).
Kick drums and bass guitars have space and distance, something I find the Sennheiser IE8s didn't do very well and the 215's place right inside your skull.
Orchestras are not warm and lush as with the IE8s which seem to place classical genres in a medium sized, musty, ornate concert hall with lots of velvet and wood.
 
 
Mids:
Nowhere near as warm or upfront as the Shures.
The snare in John Mayer's 'Belief' doesn't crack explosively with a 4KHz peak. Which is a good thing for me.
The snare is just sits about 8 meters away on a carpet in a bright room. It doesn't lack thickness, resonance or clarity but is relaxed and controlled.
 
Highs:
The articulation of highs is incredible.
Sibilance is there when it is present in recordings. It's easily noticeable, but rarely ever harsh.
There is no shimmery high 12KHz peak.
 
 
Genres recommended:
Female Vocalists
Acoustic
Classical Piano
Blues (The trumpet-playing cigar room type)
 
Genres not recommended with the Noble 4:
EDM
Full Band Rock
Funk
 
 
These are my impressions after my first extended listen.
 
 
Dug up and dusted off my PA2v2 portable amp which is well known for it's dynamic-adding definitely-not-flat properties.
It might be just batteries running low but the amount of noise from the amp is quite horrendous.
It gives driving, heavy genres more 'life' and punch, but loses the wonderful neutral composure.
If I had to rate the pairing, I'd give the pair a 70% match score.

 
 
This review is written by a regular live FOH engineer who's most similar price-range in-ears are Shure SE425's.
 
I purchased this pair (IE8) of in-ears because they were only AUD$160 from a local eBay seller, brand new w/warranty and I was interested in other sound signatures for listening to recordings. And at the time of writing this review, I have owned them for at least two months with approx 200hrs of listening time on top of burn-in.
 
I listen to a lot of live recordings and performances, female vocalists, acoustic and rock. 
I also listen to some jazz and classical, but as I am not learned in these areas I will refrain from commenting in that manner.
 
To the actual product:
 
Build Quality - 8/10
Thick and malleable strain reliefs punctuate the very decent smooth dark grey cable. All cables are actually joined via tiny PCB, from 3.5mm stereo jack to cable to Y connector to each of the earpiece connectors.
Cable is also replaceable with a skilful pluck.
Driver housing is a hard, smooth slightly metallic/glittery black plastic. Ear tip sleeve tube doesn't seem small and easily breakable.
Oh yeah, comes with a bass knob that kinda does(n't) work.
 
Comfort, Fit, Isolation - 6.5/10
Combined them because they are all closely related. 
Probably being a little harsh here, but it pretty much sucks. Seems a pity to produce a great in-earphone and a very large range of earpieces, and having them all completely miserable.  But keep in mind this comes from a person that LOVES his Shures. Isolation is a good 10dB less than my Shures, which I'm pretty much deaf to outside noise less than 95dBA in.
The foam eartips are harder than three week old crusty bread. No cushiony softness like Shure's and there's no inner rubber sleeve for rigidity either. The silicon rubber eartips are open enough and provide a semi-decent seal which turns out to be better than the foams for the IE8's to not be so bass dominant. But means the fit is a little loose, means not a jogging pair in the mean time.
Tried Audio-Technica rubber silicone eartips, hole is a little too closed, masking some of the highs.
Heard bad stories about Complys for Sennheisers, looking for alternatives. 
No moulding wire is a big sad face for me, also increases microphonics from non-existent to a recognisable level. IE8's come with detachable ear hooks, but they don't support jack all.
 
 
Sound, sound, sound - 8.5/10
These are probably a love/hate earphone.
They are definitely not well balanced or flat, but still hold an amazing clarity for >95% of my music.
They have great instrument seperation when I use them live, a sign of great fidelity.
Compared to the SE425's, they possess a greater quantity of bass, but even my SE215's have greater extension (though my 215's actually have incredible extension because of it's dynamic driver, both have the same type of driver, it's a decent comparison).
All that meaning to say, the bass hump is no lower than 100Hz, with a definite enunciation around the 160Hz. Many V-"audio"philes will be annoyed by this and won't be able to get their ears around this new found range that's really the hot ass of the body with the power that shows off the power of some female vocal recordings.
I may just be too used to the silky smooth Shure mids. Even my 215's are freakin' amazing.
Soundstage is pretty average, decent spacing, not enough distancing. Totally contrary to what other people say, I believe, who claim that the IE8's is really way up there. I don't know what kind of studios/halls/theatres/venues you work with, but it sounds more cinema than amphitheatre to me.
Vocals are warm with the relative mid-bass to mids ratio, Highs are sparkly, cymbals a little distant, not harsh enough for my liking. 
Yes, that's right, not harsh enough, there's no rawr to that rock crash. Too much *****, not enough lion. That dip around 6.3-7KHz reduces harshness too much for me, but beyond that there's plenty to a good 17KHz at least.
 
Reduces the transparency of recordings to me, sounds a little artificial, but helps lessen the pain of bad recordings. =P 
Okay, so maybe I'll say something about the forbidden genres, these do GREAT with classical.
That warmth and sparkle is really something. Just not for me. The IE8's take second fiddle for me in this price range.
Still a Shure fanboy after this.
 
 

Amps are really low-noise, even when cranked up.
Feels good with metal shell, but still lightweight.
Halo indicators are pretty useful for general levels.
 
Clips easily.
Max level input -3dBu means you'll probably need a DI still.

After burn-in and listening to them for a hundred hours or so, plus live mix time this is my perspective on their audio.
Coming from Sennheiser HD280 Pros and Shure SE215s, these seem to be amazingly balanced. 
They have the incredible Shure warmth and vocal clarity, but still extend their highs extensively. I have always found problem frequencies in all the other headphones I use, like the HD280 Pros have the weird 200Hz lump which is a constant annoying humming espesh during live sessions, biggest turn-off for me. But the SRH840s seem to be perfectly matched to the system I work with. Boominess when there is, sibilance when there is. Simply great monitoring cans for a large-ish system.
 
And the detail! Basically, if I can hear the string slap in the third minute of Tchaikovsky's Nutcracker Suite and hear pages turning throughout the masterpiece, I am completely satisfied.
The soundstage is OK. It's not amazing and a tad forward at times which you'd least expect, but those incredible highs help spread it out.
The cans do well above average for most genres but there are times you wish you had something more like the Beyerdynamic DT880 Pros or AKG 701's with a lot more air and breath to them simply because they're open, but then again, these ARE meant for professional use, and open cans would be damn annoying when you're trying to PFL/solo anything live with 90dB of background noise.
 
I seriously have been on the hunt for the best live monitoring headphone and can't find anything better for even double or triple the price.
 
There is a lot of plastic on this can, but the back of the inner circle driver housing is metal, adding to that definition I mentioned earlier while the outer casing is plastic adding to that Shure warmth. The main headband of the phone is metal based, simply because plastic will never have the same kind of elasticity, but the frame that holds the earcups is pure plastic because of the rigidity required to hold the shape.
 
I do have to complain about a few things though, mainly design-wise. Most significant is probably due to my big head. When using my HD280 Pros, dropping each side to its maximum length causes only the bottom half of my ears to be covered, but with the SRH840's I have to drop them down the whole way for them to perfectly cover my ears. Now you might ask, "then what's the problem?" As a Sound Engineer I am trained in my thinking to always have a little headroom for everything. Save some for a rainy day, that kind of thing. It's already at its limit and that leads to another problem.
This one would the be smaller cables leading to earcup. Because the side lengths are at maximum, these smaller cables are almost at full stretch and I don't know how good the strain relief is, but if there was ever to be some serious snaggage, it could mean the death of the sound in the right earcup.
 
These cans are also the heaviest, and the 4m of coiled cable doesn't help either. But it does fold away quite neatly, with the cable detachable. Too bad it doesn't fold flat.

This set is in no way flat, response wise, but I bought them because I wanted to be able to watch movies with decent audio quality without headphones. 
 
The sub is pretty decent. Too small for proper sub-bass, but bass and mid-bass are plentiful. Does tend to distort when pushed hard, and the cone on the sub is unprotected from being punctured.
 
Continuing on the V shaped tendencies, it does have quite a noticeable hill in the 10-12KHz area, I think just to make it sound like it has a lot of fidelity. But it isn't too harsh.
 
I have no idea why there's a doughnut shaped hole towards the top above the centre driver. There's absolutely no sound coming out and it's gathering a lot of dust. It's probably to fool people into thinking there's two drivers per speaker. They didn't even do that with the Z5500's so I have no idea who would be fooled into such thinking.
 
Apparently because it's neodymium there's no need for more than one driver per speaker.
 
It has pretty bad noise issues though, I'm thinking it's to do with the amp (within the sub). I stuck a ferrite bead on the power cord, looped through twice. It did halve the noise, but even when using the headphone jack on the front right speaker creates noise with head/earphones that sounds like a desert wind howling in a sandstorm.
 
Set-up takes about half an hour from un-boxing to up and running. Cables are reasonably long for a small theatre, probably inadvisable to extend them further, even though they're "balanced".
 
I wanted to hang them, but there's literally no way to hanging anything apart from the centre speaker, and even then it's bothersome.
 
Inputs are standard 3x1/8'' jacks plus Stereo RCA. 
 
I wonder if I can hijack the amp in any way....

I use these mainly for when I'm on stage or when I'm mixing live, running around adjusting a muzo's in-ears/wedges.
 
These are perfect. For 100bucks anyway.
 
But the unique thing about these I've never experience before is that it makes me want to see how far I can turn down any track and see how far I can go before I lose those details I've never noticed before.
 
They simply sound capable of reproducing whatever you throw at them. Sounds are no longer squished together. I can now discern clearly what level instruments are relative to others as opposed to something sent through a compressor with a hard knee and ultra high ratio. i.e. it sounds very clear, linear and distortion-less.
 
They come with a perfect little flat oval case with the Shure logo stitched on. Very nice and pro-looking.
 
Complaints. Hmmm.
 
They do lack a certain brightness, making cymbals, etc. sound slightly distant. But they demolish listening fatigue. Hours of listening, and normal hearing 
They don't lack space, they just don't shimmer as much. Which really reduces listening fatigue during long gigs and rehearsals.
When listening to music, it's very raw and clean. It doesn't try too add something that isn't there, but everything that's meant to be there is.
 
The cable is a little stiff (plus heavy and thick), and being an engineering student, I know that it is a little too stiff for massive amounts of bending, which a bit of a downer, because I needed a running pair, too. But it's all good, 'cos the cable is replaceable! Albeit a little pricey, it's ultra simple and easy with the snap connector. Some people have complained about the swivelness of the connector, but I find it makes it a whole lot easier to get them on, and it feels sturdy enough.
 
So that's about it.
 
 

Used these mainly for jogging. They fit great for me, a little intrusive, but they never ever came out when I ran. Great sound for the price (at the time.)

Wasn't impressed by the packaging or the build quality, though it was cheap, I still expect Sennheiser to have some kind of standard. A lot more went into the nice fake leather case which fits many but the biggest of iPods very nicely.
The volume control is quite fluid in motion and won't move easily on accident, but both it and the Y-split are very cheap and plastic looking/feeling. Especially the clear plastic over the CX280 label.
But the reliefs on each earpiece is sturdy with a slight give and the gold-plated right-angle 3.5mm plug has survived many a knock and many a sit on.
The cable is a bit tangly, being rubberised, friction is quite high and the cable is microphonic at  a decent touch.
Earpieces come in the standard single flanged three sizes.
Sound, though, is extremely suprising. The soundstage is amazingly broad and deep, something expected of maybe a 200ish dollar headphone/IEM. Quite V shaped in it's EQ, but they still sound better than $150 Shures.
Mid-bass is not boomy, (even a little lacking sometimes), but listening to John Mayer's: Where The Light Is, Steve Jordan's kit sounds amazing. The snare is tight and cracking, the kick is powerful and punchy and never bloated, the ride and the crash send tingles up my spine, Palladino's bass really drives the mix and Mayer's voice could be right there, live in front of you if you closed your eyes. It does get quite harsh if you really push the volume, but I love listening to classical and falling asleep with these on because it's so light, clear and airy that it doesn't seem like anything's actually inside my head and I don't have to worry about breaking them because they're so cheap!
These are really ideal if you listen to live recordings and want to experience to moment again.
Not so much pop/hip-hop, but you'll be amazed at the sound of Mtislav Rostropovich's Bach Cello Suite through these.
Sennheiser has really put a budget competitor out there to beat.
 
Burn-in takes a good 24-hours. Well worth the wait and the insanity freq sweeps bring.

Full review and pictures of the NON-mic and controller version (D510) here.
http://www.head-fi.org/forum/thread/538180/denon-ah-d510