GMR-540-A-ISO
headphones
$130
Used market: $100*
Specifications
4 of 7 values have a recorded sourceExpert Audio Engineering Commentary
Tonal Profile
The closed («ISO») version of the same gaming headset. Closed cups raise isolation and change the bass, but Koss publishes exactly the same electrical data as for the open AIR version.
Amplification Warning
Same load as the AIR: 35 Ω, high efficiency, driven by anything with a jack. Pick between the two by how much of the room you want to hear, not by what will power them.
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.
«Impedance: 35 Ohms — Sensitivity: 103 dB SPL — Frequency Response: 15-22,000 Hz»
Every electrical and acoustic figure on this page is identical to the open GMR-545-A-AIR: 35 Ω, 103 dB SPL, 15–22 000 Hz. An open and a closed enclosure cannot measure the same frequency response at the low end, so at least one of the two sheets describes the driver rather than the finished headphone. Treat the numbers as a driver specification shared by both products, not as a measurement of either.
checked 8/5/2026* Estimated with the depreciation fallback (~77% retained value). · checked on 8/5/2026