The Koss KSC75 are budget on-ear headphones with a stable ear-hook design. They're compact and will easily fit into your pockets. They also have an open design and a decently well-balanced sound which makes them a very affordable critical listening option but they may lack a bit of bass for more casual listeners. Unfortunately, they're not very durable and look a little cheap.
The KSC75 aren't the best-looking headphones but they're lightweight and have a stable fit. Thanks to their ear-hook design they will rarely fall off your ears unless the non-detachable audio cable gets hooked on something. They're also easy to carry around on your person but do not come with a case. Unfortunately, they do not have any controls and their build quality does not feel very durable. The cable is flimsy and the ear cups look and feel cheap.
The KSC75 are lightweight and moderately comfortable headphones. They're on-ears with an ear-hook design that's stable but slightly uncomfortable. The hooks put a bit pressure behind your ears at first, and it's particularly worse if you wear glasses. However, the hooks stop feeling as intrusive after having the headphones on for a while.
These headphones have a small footprint and are quite easy to carry around on your person. They have a simple ear hook design, so they do not have a headband, and you can easily fold and fit them into your pockets. They do not come with a good case however, which is a little disappointing.
The build quality of these headphones is sub-par and feels cheap. The ear cups are not particularly dense, and they have thin non-replaceable audio cables. They're lightweight headphones, so they won't get damaged by a shoulder height drop. However, their build quality doesn't feel durable which is to be expected for their budget price range. On the upside, they also benefit from the Koss limited lifetime warranty.
The KSC75 have an ear hook design that's stable enough to run with. They're lightweight and barely move once you achieve a good fit. Unfortunately, they have a non-detachable cable that may get caught on something and yank the headphones off your ears. You can limit this issue by passing the cable under your clothes, but this means they won't be the ideal headphones for the gym or strenuous exercises.
The Koss KSC75 is an average sounding pair of open-back on-ear headphones. They have an excellent Mid Range, an open Soundstage, and perform very consistently across multiple humans. However, their Bass lacks low-end thump and rumble, their Mid Range sounds slightly muddy and their Treble is on the bright side. They also have a mediocre distortion performance, especially in the Bass Range.
Mediocre Bass Range performance. Low-bass, responsible for low-end thump and rumble, is lacking by more than 9dB which is typical of most open-back on-ears. Bass is relatively balanced but shows a tilt towards high-bass. High-bass is overemphasized by more than 3dB, adding a bit of boominess to the sound.
Very good Mid Range performance. Low-mid is over our target by about 3dB, making mixes slightly muddy and cluttered on these headphones. Mid is very consistent and well-balanced. High-mid shows a bit of tilt towards higher frequencies, nudging the upper harmonics of vocals/leads to the front.
Below-average Harmonic Distortion performance. The KSC75 shows high amounts of harmonic distortion, regardless of the level, in the Bass and the Treble Ranges. This will have a noticeable negative effect on the clarity and purity of Bass, and would also make the higher frequencies sound harsh.
The HSC75 have an open design not meant to isolate listeners from ambient noise. Noise easily seeps into the ear cups which produces a more immersive listening experience but also means they won't be ideal for loud environments, like commuting via public transit. They also leak quite a bit and would not be suitable to use in quiet settings, as they might distract the people around you.
Poor Isolation. Due to the open-back design, these headphones isolate very little. They provide no reduction in outside noise in the Bass and Mid Ranges, and provide only 3dB of isolation in the Treble Range.
No active features.
The Koss Porta Pro are a slightly better headphone overall when compared to the Koss KSC75. The Porta Pro have a better-balanced sound and a more comfortable on-ear fit that you can wear for longer than the KSC75. The Porta Pro also have a better more durable design, although not by much. On the upside, the KSC75 are bit more portable and have a slightly more stable design if you plan to use them for sports.