AudioChainsDB
Koss

Porta Pro

headphones

$50

Used market: $35*

Manufacturer datasheet

Specifications

4 of 8 values have a recorded source
Connector
3.5 mm·
Form Factor
On-Ear·
Is Closed Back
no·
Impedance ohms
60✓
Transducer Type
Dynamic·
Detachable Cable
no·
Sensitivity dB mW
101✓
Release Year
1984·

Expert Audio Engineering Commentary

Tonal Profile

In production unchanged since 1984 and still one of the few consumer headphones whose datasheet names the unit: 101 dB SPL/1mW at 60 Ω. Open, supra-aural, with a folding steel headband and a bass shelf that has outlived every fashion in tuning.

Amplification Warning

60 Ω is high for a portable, and that is deliberate: it makes the Porta Pro tolerant of a bad jack and quiet on a noisy one. 101 dB/mW gives about 113 dB from a volt, so no source in this catalogue struggles — but a phone dongle at half volume is already loud enough to matter for hearing.

* Estimated with the depreciation fallback (~70% retained value). · checked on 8/5/2026