Intro:
After selling my Sony XB-500's, all I was left with was open back headphones, so I needed a pair of portables for school. I was originally going to Purdue the AKG Q350 IEM's, but I didn't have enough money, so when I saw this on amazon for $30.00 with tax, I jumped on it.
Design Overview:
The AKG K340's are probably the LIGHTEST in-ear monitors ive ever held, and that combined with the super soft eartips, leads to great comfort. They have a WIDE nozzle, so most standard ear-tips wont fit on them. They ear-tips they do come with isolate fairly well, and add almost no flavors to the sound of the monitors. The cable is VERY light, and can be prone to microphonics. The only real problem is the volume slider right before the split in the cable. It's big and bulky, and does NOT feel strong. Its easy to bump the slider, and mess up the volume. I prefer what comes on the Q350, but then again, I paid $30.00 for a pair of great sounding monitors.
Sound:
I REALLY enjoyed the sound of my Grado SR-80i headphones, and at first, these sounded just like them. Not very much bass, good clean mids, and a bit sparkly highs. After a couple days of use, I noticed the bass become more prominent, and the highs recede a bit. At this point (un-amped) they sound like a ln in-ear cross between XB-500's and Grado SR-80i's. Presentation is clear, and quick.they've definently warmed up over time, but their mids are still there. Recently, I'd gotten a portable amp (FiiO E7, and I was INSTANTLY blown away by their new sound. Bass tightened up, mids got a fresh cleaning, highs became super quick and very clear. The overall presentation (for lack of a better term) just got a lot clearer. I also (for the first time) noticed some soundstage to in-ears. With the small ear-tips, bass becomes a bit more sloppy, and with the large tips, the stage opened a bit, although the flavors remained relatively the same.
Music Recommendations:
Sounding like Grado's the first thing id recommend for these would have to be rock/metal. These pair fairly well with Rush, and are OK with Dream Theater. Pink Floyd ("The Division Bell" especially) really comes to life, and sounds clear and full. Amping these was the first time I really heard Guns 'N Roses sound very clear. The guitars of 'Welcome to The Jungle' really cleared up ad made me grin. Electronic music is just sorta "meh" on these, as is classical. Jazz is veeeeery good, especially Miles Davis' "Kind of Blue". 'I Talk to The Wind" on King Crimson's "In the Court of the Crimson King" shines,and were the first WOW factor for these IEM's for me. For portable use, at a loud high-school, and noisy bus, these keep their sound fairly well. Would DEFINENTLY recommend if you can get them <$55.00

I ordered this, and when it gets here I will write a full review. The scores are based on what I've seen, and heard of it.

I got these used from my friend because I wanted a closed back can for walking around school with, and he was selling them like-new (2 hours max) for $20
 

Sound

I absolutely love these headphones, and their warm luscious sound was a nice change from my Sennheiser HD518s. These can be run clearly and cleanly out of almost any source, although if you REALLY want brain mashing bass, a FiiO e7/E17 with bass boost will smash your skull.
Signature:
Don't get me wrong if you think that these are just a basshead's cans, these have clear sound throughout the spectrum, the highs sparkle, the mids come through clear and present, and the bass, well, the bass is thumpy, and just sounds fun.
Nit-picks:
Their soundstage isn't as wide as my HD518's, it is still quite good, especially for a closed can. It has a very IMMERSIVE sound, and vocals can sound as close as up to your ear, or sound like they're a mile away. It has more of a fun than a critical sound.
 

Design

The design has some flaws, but not many, or any deal-breakers.
Pros:
1.) The flat cord is a lot more useful than you'd expect, it really does keep it from tangelling, but with that comes a downside (mostly for me and other OCD people) in that the cord becomes 'wavey' when you lay it flat.
2.) The ultra-light headband is awesome, and really trims down on the weight.
3.) The sliding motion of the headband is smooth, and easy to pick notches, while not slipping while you're wearing it
4.) Earpads get warm within an hour, but usually a quick lift off of your head will cool it down.
Cons:
1.) It seems to me that either 1. the Y split is too far down the cable, or 2. the cable is just too short
2.) where the black rubber connects to the silver plastic on the earcup, they separate, and feel really loose.
3.) Although the vents on the earcups do help with overall sound, it makes them leak noticeably, and it doesn't isolate as well as it could.
4.) Earpads are very squishy, people in the hallway come up and squish them sometimes XD.
 

Final Notes

I love these cans, and would definitely recommend these if you can find them for less than $75 USD. A basshead would love these, and so would the average person. If you're looking for a set of critical listening cans, these are not it. These have a very warm and fun sound. Great for rap/hip-hop/pop/ALL electric music, or other bass heavy music. Decent with rock/metal, but not very good for classical, or jazz. These are great headphones, and if you end up buying these, I hope you enjoy them as much as I have.

i bought these buds several months before being introduced to the Hi-Fi community, so i had no idea what to expect. they look quite snazzy, reviews were good, so i clicked "buy" on amazon. they arrived, and i immediately started jamming out. i loved them, and wore them 24/7. my friend mentioned a 'burn in' so i googled it, and gave it a whirl with 20 hours of Dream Theater, Rush, and Iron Maiden. I picked them up the next day, put them in my ear and nothing had changed. at all. i kept loving them for a good 5 months till i ordered my Sennheiser HD518's for my birthday. I LOVED the senns, they sounded IMMENSELY better, and i wore THOSE 24/7. i put the buds back in, because we had to go out to do errands, and realized just how heavy the bass is. the bass was pushing all the other parts of the music just right off the stage. i'd never noticed, because id never had anything to compare. these would be perfect for a bass head, but for someone who want clean, BALANCED sound, stay away from these.