AKG K403

Great lil on-ear headphone but a lil bit uncomfortable on ear.
Not for someone who loves heavy bass but good for seeking clarity

My opinion, my first AKG product. Tried the AKG Y50 but to me, this one sounds better at details (i guess due to semi-open back design?)(Y50 is a bit too much sub bass but is still not like Beats).
I dont really like the Y-cable style but thats my preference.
Can be comparable to Beyerdynamic DTX710 by its sound but way more portable (from my view. i need to test DTX710 again later).
The advertised 3D-axis folding mechanism is kinda weird though. Is good when you want to fold back into a small bag or pocket but this doesnt come with a headphone bag, plus, im kinda the person who always hang his headphone on his neck anyways.
 
The headphone seems to be louder than my daily Philips SHM7110 though advertises same 32 ohms impedance.

Sounds great but not for kickin' bass lover. Though this can be a quick fix if you tune up 32Hz@3-4dB and 64Hz@2-3dB with your equalizer. with my a bit taste, i would tune down a bit 125Hz about 1-2dB.
To be honest, the pads for this headphone make this headphone uncomfortable. the sponge makes somewhat my ears a bit ichy and course feeling (hope that 3rd party pad do have a bit more silky). the clamping is a tad forcy but not in the way that makes me a headache, though the small top pads do make me kinda having someone pusing 2 pins on my head.

Havent burn this thing down but guess will do for a month

*im kinda into audiophile world but i dont have yet experiences awesome headphones but tried most on shops.
Pros:
1. Good sounding without burn-in. (will burn it eventually)
2. Great detail.
3. Obvious lightweight and small
4. True open-back headphone (semi-open)
 
Cons:
1. Audio quality is great but bass side is a bit underpowered
2. The pads are uncomfortable that somehow they itch your ears!
3. 3D-Axis folding mechanism is a bit complicated
4. Feels cheap and not durable (the jack shielding seems to be one of the cheap jack that can be easily damage and snap the internal wire)
5. As portable as it gets, the wire arein't foldable or 'can be shorter' (i mean something like wire attractable??)
6. since this is open-back (well, semi-open), the sound leak is, well, quite audibly far enougheven though im at my usual volume (or actually, lower)
7. i dont know if $50 is cheap for this headphone. (or is just mine is pricier due to the shipping requirement)

*song albums tested, Dalf Punk - Random Access Memories album (FLAC 24bit 88.2kHz), The Queen - Greatest Hits (FLAC 24bit 96kHz), deadmau5 - For Lack of a Better Name (FLAC 16bit 44.1kHz), 40mP feat. Hatsune Miku - Chiisana Jibun To Ookina Sekai (FLAC 16bit 44.1kHz)

After reading the reviews i was expected much worse in the way of comfort. The clamping force was a tad strong but the flexible metal band was easy enough to bend for a lighter clamping force.
After that basic adjustment it's like a couple of clouds floating on my ears
 
The sound can be very detailed especially if you cut away a sizable hole in the foam covers. Bass is adequate however it won't dig much below ~40hz-50hz so maybe invest in a bass shaker as well.
The imaging is excellent and has the full 360 degree 3d sound field i've been looking for in a cost effective set of headphones.
 
The drivers appear to be 40mm.
Plenty of wow moments that might be hard to find with other cheap headphones. It would be good if someone can compare these agains't the Koss ksc75.

 
This was the first AKG product I purchased. I decided to try a more affordable model to get an impression of the AKG sound. I bought this for $28 on a clearance sale, a major discount from the MSRP of $99.
 
Sound
 
From the moment I played the first track on these, I was blown away by the overall sound signature of this headphone. It is very clear that AKG put the money into what matters, the drivers. AKG took away all the fancy stuff, a no frills approach, and put your ears as close as possible to their investment (the drivers). The bass is punchy and tight, more so than many other open headphones I own at more than double the MSRP of this. The mids are incredible, in your face and up front, where they should be. These are very easy to drive, and as a result, get really loud, even from portables. For those who listen at high volumes, you will love this, it gets louder than any headphone I have tried. The sound stage is average, especially for an open design, but the outstanding bass, mids, and volume more than make up for this. The overall sound signature is great for any genre of music.
 
Design/Comfort
 
Honestly, from first visual impression, I was surprised to see it with such a high MSRP, it looks more like a sub $40 headphone. After opening it up and trying it on, I realized the plastic and metal is above average quality, it looks cheap but don't be fooled, it's well made.
 
Comfort overall for me was acceptable. I wear glasses, and most on ear headphones get uncomfortable after a while. These did get uncomfortable after 1-2hrs of use. The discomfort for me comes from the ears due to the clamping force and minimal padding over the drivers. I find this gets a bit better over time as the headband stretches out. Because there so light, the little headband pads are adequate, and I feel no discomfort there. 
 
They look good when there on, they are sleek and minimalistic, people will barely notice them. Once there on, they stay put, even when running/exercising. Since there so sleek, you can easily put a hat or toque over top. The folding design and small size is perfect for portable use, however, because there open, I do not recommend using these in quiet public places.
 
Verdict
 
These represent the AKG sound signature very well at a great price point. The design is simple, and no frills. The money goes into what matters, the drivers. AKG takes away the fancy stuff and gets you as close to the drivers as possible. You hear the difference this makes immediately. I highly recommend these, specially if you can get them under $50. I have been a loyal Sennheiser user for years, but AKG has won me over with these. I will be looking at AKG for my next $200-300 purchase now.

I got this as an impulse buy while I was living in Seoul. I already own the Audio Technica EM7 (which are amazing, BTW) but they were a mess when I had to take them on and off around Campus (although they are great for the street). Boy was I surprised. Their sound is very similar to the Koss PortaPro even when the driver is completely different. It is certainly fuller even when it doesn't seal as well as the PP. The bass is rich and relatively tight for an open design and the other frequencies are almost distorsion free. Unlike the porta pros, these won't trap your hair in the headband as once it's adjusted, it won't move ever again. They fold both flat and in a compact sennheiser PMX like shape. the cable is short and tangle free, too. 
 
Now, what's not good at all is the comfort: unless you wear them in a certain, very specific way, they will hurt your ears in an extremely painful way. The cups rest directly over your ears, and they only have a little foam between your ears and the prominent plastic ring that holds the ear pad. the PPs solve this with the temple pressure adjustment so the pads don't rest directly over your ears. 

short terms:
compact, loud, nice sounding, cheap ultraportables.
 
detailed terms:
AKG in the house ( fun, smooth, bassy, bright-warm & clear presentation )
cool for mainstream song including R&B, but not so for bass heavy genres  
 
you can describe it as a lesser-hifi than K420 for half of its price