KPH30i
headphones
$30
Used market: $25*
Specifications
4 of 7 values have a recorded sourceExpert Audio Engineering Commentary
Tonal Profile
The third member of the 60 Ω Koss family, with an in-line microphone and the same published numbers as the Porta Pro and KSC75. The suspension headband is the only genuinely different part.
Amplification Warning
Driven by any source. The in-line microphone means a 4-pole plug: on a PC with separate jacks you need a splitter, and on a splitter of the wrong wiring standard you get sound but no microphone.
What the datasheet actually says
Quoted verbatim from the manufacturer’s own page, with the date we checked it. We state what is printed, not what anyone intended by it.
«Sensitivity: 101 dB SPL»
Koss prints «101 dB SPL/1mW» for the Porta Pro and the KSC75 and the same value without the «/1mW» here. Because it is the identical number from the same maker on a headphone of the same impedance, we read it as dB/mW. This is a case where the omission is harmless — but it shows that even a manufacturer with a clear convention drops the unit on some pages, so the unit can never be assumed from the brand alone.
checked 8/5/2026* Estimated with the depreciation fallback (~83% retained value). · checked on 8/5/2026