
Disclaimer: I bought this at my own expense at amazon.se
Price: 20-30 usd (I paid 30 usd)
Specifications:
Frequency response: 15-25,000 Hz
Impedance: 60 ohms
Sensitivity: 101 dB SPL/1mW

Accessories:
None

Cable: A simple cable that is the type that is on most mainstream products. Durability should be fine due to the thickness but the weak point is most likely the connectors on the drivers themselves as they don’t have any strain relief there. It has a diagonal plug at the 3.5mm connector.

Build: The build quality is like a double-edged sword; it is plastic (not very high-quality plastic) but is also very lightweight due to it. Very minimal adjustments can be made in terms of adjusting the angle of the driver. Unfortunately, no L/R markings.
Fit: Very unique fit but no problems for me. Although it doesn’t fit secure enough to be used in physical activities.
Comfort: Extremely comfortable and almost weightless on my ears. Very little heat generation due to the fit (no clamp since it doesn’t have a headband). It shouldn’t be a problem even for hotter countries.
Isolation: Basically, non-existent isolation and it leaks a lot of sound, definitely not something to use in a public place like a library.
Setup: Ibasso DX160 (high gain, volume around 45), stock cable, stock pads
Lows: Very clean bass due to it being very tight/fast but extension and rumble is extremely bad so it is not suited for sub-bass focused genres like EDM, Hip-hop, Trance. Mid-bass on the other hand is better in quantity but is still lacking, but it is very suited for acoustic tracks.
Mid-bass: Metallica – fight fire with fire (01:11-01:52), Very good speed, tightness and texture so it sounds extremely clean and no signs of bloat at all. Quantity is fine for this track but I prefer a bit more so it is more fun. The (02:55-03:01) section is very good and you can hear the chopper very well.
Hiroyuki Sawano – Pretenders (01:18-01:47), Very tight and fast, but is lacking some quantity along with texture to make it fun and to make it more tonally correct (it needs to be warmer).
Sub-bass: Djuro – Drop that bass (01:15-01:30), Extremely bad extension and non-existent rumble. The punch is clean because of its tightness/speed but is also lacking a lot of quantity along with texture.
Will Sparks – Sick like that (03:08-03:22), Very tight and fast but is lacking quantity and texture.
Mids: Extremely high-quality female vocals and very good male vocals. Balancing between male/female vocals is leaning a bit more towards female vocals due to the overall tonality being on the brighter and thinner side. Male vocals are a step behind the female vocals in terms of quality, due to it sounding a bit too bright/thin. But both male/female vocals are very detailed and sounds very clean.
Female-vocals: Hiroyuki Sawano – OldToday (01:25-01:52), Stunningly good, the tonality is very good for this, thin but not too thin and not too bright. Vocals are very clean and detailed. Excellent timbre, just a little bottlenecked in terms of naturality due to the low bass quantity making it lack a bit of warmth for the instruments.
Yuki Hayashi – MightU (01:58-02:55), Extremely natural and tonality is correct.
Evanescence – Bring me to life (01:18-01:35), A bit too bright tonally and a tiny bit shouty.
Hiroyuki Sawano – Crescent (02:07-02:26), Is a bit shouty and too bright tonally.
Male-vocals: Hiroyuki Sawano – Pretenders (00:57-01:17), Needs to be a bit warmer for both his vocals and the instruments, but otherwise very clean and natural.
Hiroyuki Sawano – Scapegoat (00:57-01:17), Lacks some warmth but is very clean and natural.
Treble: Linkin Park – Shadow of the Day (03:24-03:42), Not sharp at but is a bit too bright.
Deuce – America (03:03-03:16), Tonality is too bright.
Hiroyuki Sawano – Lose (string version) (01:22-01:59), Tonality on the violins are very good, but texture could be better. Cello´s needs some more warmth but is better textured than the violins.
Hiroyuki Sawano &Z (02:18-02:57), Very natural and clean sounding, but needs a bit more bass quantity.
Soundstage: Huge soundstage in both width/depth but is wider and is very airy.
Tonality: Bright-neutral with excellent timbre. Thinner note weight but not too much so it becomes analytical.
Details: Very impressive amount of details (and yeah, the tuning does have its inherent benefits to the technicalities).
Instrument Separation: No problems at all, very impressive (low bass quantity and very fast/tight certainly helps it a lot).
Music: Fate grand order Babylonia – Hero´s mission, sounds absolute fantastic with its natural timbre and the huge soundstage makes it epic while the technicalities can keep up.
Hiroyuki Sawano – Because we are tiny in this world, extremely natural despite the bass quantity being very low. Somehow sounds fun (with low bass quantity) and yet is very clean and detailed.
Songs that highlight the Headphone: https://www.youtube.com/watch?v=hsXur-NbfG8 https://www.youtube.com/watch?v=3jf_Z68c4LQ https://www.youtube.com/watch?v=vLhafvJvPUI https://www.youtube.com/watch?v=Ek7C5GurYOw https://www.youtube.com/watch?v=gk-mrXzjQo4 https://www.youtube.com/watch?v=8F_11HaH4mE
Good genres: Acoustic music, OST
Bad genres: EDM, Trance, Hip-hop, R&B
Comparisons:
Headphone: Koss Porta Pro, stock cable, stock pads
Bass: Djuro – Drop that bass (01:15-01:30), Better extension and rumbles much more on the Porta. While the 75 has a faster and tighter punch so it is much cleaner, texture is similar on both.
Hiroyuki Sawano – Pretenders (01:18-01:47), Bloated bass on the Porta, while it is very clean on the 75 due to its much faster/tighter bass. Texture is a bit better on the 75.
Metallica – fight fire with fire (01:11-01:52), While speed is somewhat similar, the Porta is extremely bloated due to it being very loose. To the extent that it almost sounds like sub-bass rumble instead of mid-bass punch. Individual bass strikes are meshed together on the Porta while it is extremely clean and detailed on the 75. No contest at all, the Porta is literally dying from blood loss (bass bleed).
Mids: Hiroyuki Sawano – OldToday (01:25-01:52), Tonality is much better on the 75, while it is too warm and dark on the Porta. Much cleaner and detailed on the 75 as well.
Evanescence – Bring me to life (01:18-01:35), Tonality is much better on the 75 and is much cleaner and detailed. The bass on the Porta is affecting the tonality very bad (too warm).
Hiroyuki Sawano – Scapegoat (00:57-01:17), Tonality is more correct on the Porta, but is much cleaner and detailed on the 75.
Treble: Linkin Park – Shadow of the Day (03:24-03:42), Tonality is better on the 75 and is cleaner, more detailed and more natural.
Hiroyuki Sawano – Lose (string version) (01:22-01:59), Tonality is a bit better and more textured with the cello´s on the Porta. Violins are much more tonally correct and textured on the 75. Much cleaner, detailed and natural on the 75.
Hiroyuki Sawano &Z (02:18-02:57), Better tonality, detail, cleaner and more natural on the 75.
Technicalities: Shiro Sagisu – Hundred years war (02:24-02:57), Soundstage, detail, instrument separation and timbre are on another league on the 75.
Overall: The 75 beats the Porta on pretty much everything except bass quantity. So, for bass focused genre like EDM, Trance, Hip-hop and R&B, the Porta is more suited for those. While the 75 is better on everything else. Although if you want most fatigue-free sound, the Porta is better due to having both lower treble quantity and much more bass quantity.
Earbud: NiceHCK DIY MX500, stock cable, full foams
Bass: Djuro – Drop that bass (01:15-01:30), rumbles and extends a bit more on the MX500. Punch quantity is also a bit higher on it. The 75 is tighter, faster and has a bit more texture.
Hiroyuki Sawano – Pretenders (01:18-01:47), Quantity is similar but is tighter, faster and more textured on the 75.
Metallica – fight fire with fire (01:11-01:52), a bit more quantity on the MX500 but faster and tighter on the 75 while texture is similar.
Mids: Hiroyuki Sawano – OldToday (01:25-01:52), Similar tonality but much cleaner and more detailed on the 75.
Evanescence – Bring me to life (01:18-01:35), MX500 is a bit more tonally correct and less shouty.
Hiroyuki Sawano – Scapegoat (00:57-01:17), more tonally correct on the MX500 due to having some more warmth (due to having a bit more bass quantity).
Treble: Linkin Park – Shadow of the Day (03:24-03:42), less fatiguing on the MX500 and also more tonally correct.
Hiroyuki Sawano – Lose (string version) (01:22-01:59), Cellos are more textured on the 75 but similar tonality and timbre. Violin timbre is a bit better on the MX500 but has similar tonality and texture. Cleaner and more detailed on the 75.
Hiroyuki Sawano &Z (02:18-02:57), Tonality is better on the MX500 and sounds more natural, while it is more detailed and cleaner on the 75.
Technicalities: Shiro Sagisu – Hundred years war (02:24-02:57), Soundstage, detail, instrument separation, imaging and timbre are better on the 75.
Overall: The 75 has better SQ and technicalities but is less versatile due to it having less bass quantity (not that the MX500 would suit bass heavy songs much more than the 75 though…). The 75 is perceived as being brighter overall all due to the bass quantity but treble quantity should be similar.
Headphone: Blon B20, Brainwavz Sheepskin Leather Memory Foam, YY 16 core cable 3.5mm
Bass: Djuro – Drop that bass (01:15-01:30), Extends and rumble much more on the B20. Texture is a bit better on the B20 and has more punch quantity. Tighter and faster on the 75 and is cleaner and more detailed.
Hiroyuki Sawano – Pretenders (01:18-01:47), Similar quantity, but tighter, faster and more textured on the 75.
Metallica – fight fire with fire (01:11-01:52), Faster and tighter on the 75 while texture is similar. Individual bass strikes on the B20 is pretty bad and not very accurate.
Mids: Hiroyuki Sawano – OldToday (01:25-01:52), Tonality, details and clarity is better on the 75. But the difference in timbre is very big, the B20 sounds very unnatural.
Evanescence – Bring me to life (01:18-01:35), Tonality is a bit better on the B20 and is less shouty.
Hiroyuki Sawano – Scapegoat (00:57-01:17), Tonality is a bit better on the B20 due to it being warmer, but again the details, clarity and timbre is much better on the 75.
Treble: Linkin Park – Shadow of the Day (03:24-03:42), Tonality is a bit better on the B20 due to it being warmer, but again the details, clarity and timbre is much better on the 75.
Hiroyuki Sawano – Lose (string version) (01:22-01:59), Everything is better on the 75….
Hiroyuki Sawano &Z (02:18-02:57), Everything is better on the 75….
Technicalities: Shiro Sagisu – Hundred years war (02:24-02:57), Soundstage is deeper on the B20 while width is similar. Details and instrument separation are better on the 75. Imaging is similar. But the timbre is disgustingly bad on the B20, extremely unnatural.
Overall: DO NOT BUY THE B20! It doesn’t offer anything over the 75 despite the giant price difference and on top of that it also doesn’t have the godly mids that planars should have while it has a very unnatural planar timbre across the entire range.
Conclusion: In conclusion, for acoustic music listeners, the Koss KSC75 is a 5/5. But If you aren’t only listening to acoustic music, then it is a 4.5/5 because the bass quantity is bottlenecking it a lot for other genres. Thanks for reading.
Reference/test songs: