They have very good sound quality without the bass overpowering, and they are lightweight with good support, which means you can use them for hours without discomfort. At their price, I don't think there are better headphones.

They have very good sound. The fact that it doesn't isolate all the surrounding sounds, I consider it an advantage when using it for walking on roads with vehicles, but this doesn't prevent someone from hearing the very good and musical sound they reproduce! They are definitely worth their money... and believe me, I don't settle for mediocre sound... as I have spent a lot of money on good listening experiences at home and in the car.
The bass, for me personally, is more than enough. Maybe the younger ones would want more, but I have to tell them "not in the quantity, but in the quality lies the abundance"

I have read and heard the best about these headphones before deciding to try them myself.
They are very pleasant headphones, indeed. I haven't heard countless headphones to compare. That is, the ones I have heard in recent years were of good reviews but overrated in my opinion.
The kph30i, due to their price, I consider them definitely not expensive, although they are very cheap in terms of touch and construction feel. That is, we have reached a point where you pay €40 and what you buy is not a serious construction. I don't think it's right, it's a shame.
Yes, I listen to music very pleasantly. But if they break quickly, what can I do? I will come back if there is such a development in the end.

EDIT: As expected, they broke easily. For someone who wants a decent pair of headphones in terms of sound quality, they are excellent, as long as they take care of them like their own eyes.

The only thing I have to say is how sorry I am for the hundreds of euros I have wasted so far on mediocre headphones. Who would have thought that one day, thanks to Koss, you would only need forty to have such enjoyable sound in your ears...

Well guys, having read the reviews for the product and the company I was tempted to buy them, but with low expectations. I received them today, as soon as I plugged them into my pc to listen to music on YouTube, I was blown away. The sound is very full and sweet, in a few words, the sound of much more expensive headphones. If for some reason you can't find them available...order them! THEY ARE WORTH IT A THOUSAND TIMES!

If someone told me I wouldn't believe it... headphones for 40 euros that have the sound quality of 200 euros??? Yes, it sounds stupid...
And yet, it's true... and from an ON ear open back headphone that seems like a joke with mediocre construction.
I should mention that I own several... Hd599,600,650,660,Sundara,DT1990,DT770,M50X,XB900N,XM3, Beyer Soulbyrd, Clears, etc, etc, etc.... I also had some On ear headphones like the HD 25, BW P5 but they didn't suit me.

Well, in my opinion, these have better sound than most on the list, they are so flat, so high resolution without being bright (class above the DT Beyers) and much superior to other On ear headphones that cost more.
Soundstage that you wouldn't expect from ON ear headphones and yet it's there, bass that is very fast, much faster than the Dt770 (although not as deep) and not bloated like in the M50X, XB900n, XM3... it reminds me of the bass of the HD 25 but lower, the mids are clear, the highs crystal clear with such a warm veil...

They are so good that they reach 80% of what the HD 600 + HD 650 can offer and 70% of what the HD 660s can offer, I believe that says it all.

Buy them YESTERDAY, what are we even talking about, 40 euros??? I wouldn't even consider it and with a lifetime guarantee?

Value for money award 2020. I have had them for about a year now from abroad and I use them as my everyday headphones on my PC. They may seem cheap, but the sound they produce is incredible. And I'm not comparing them to fake Bluetooth headphones from unrelated brands, but to headphones in the range of 200-250 euros from audio equipment manufacturers that people buy for MUSIC!

Sound: Simply unbelievable. The highs are crystal clear, smooth a.f., and even though we're talking about on-ear headphones, they don't hurt your ears. You can distinguish every instrument playing above 8Khz and the imaging is wonderful. They have a large soundstage in a way that I don't understand for on-ear headphones, although the fact that they are semi-open helps with that. The mids and vocals sound like the singer is right in front of you, not at all V-shaped so that they are pulled back and you lose details. Their bass is perhaps the biggest mystery for me because we're talking about something so small that almost (and I emphasize almost) reaches fidelio X2 levels.

Build: Yes, they are made of plastic, but not cheap plastic. They require attention in how you handle them and if you avoid throwing them on your desk or in bags/purses, they will last for a long time. If their "journey" is from your ears to a stand and back, then they won't suffer anything at all.

Comfort: Lightweight, in terms of weight you don't even realize you're wearing them. The only negative is the pads they have, which after a while heat up your ears. Also, the texture of the sponge is a bit "rough" and you will notice the skin that comes into contact with them drying out and peeling after a few days. You can change the pads (maybe yaxi pads), but they cost as much as the headphones themselves and you risk breaking them because the sponge is tightly attached to the plastic feet that hold the two sides of the headphones together.

All in all, for anyone who wants to "experience" an audiophile experience and not spend a fortune, they should buy them, find the music they like to listen to in good quality (flac), and simply be shocked.

For those more knowledgeable in the field of sound, get them to see the god-like sound quality that a headphone that costs only 40 euros can achieve.