T20RP mk3
headphones
$110
Used market: $85*
Specifications
3 of 7 values have a recorded sourceExpert Audio Engineering Commentary
Tonal Profile
The open member of the RP trio, aimed at long monitoring rather than isolation. 92 dB/mW into a flat 50 Ohms is genuinely insensitive: 100 dB needs 6.3 mW, or 0.56 V, so a phone reaches it but a weak laptop output runs out of headroom on transients. The rated 3000 mW is a durability figure and is not a requirement on the amplifier.
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.
«model (e.g. of a vehicle) Open RP dynamic type / driver (of a vehicle) RP diaphragm»
Fostex labels the RP series 'dynamic', and in the loose sense of an electrodynamic transducer that is true. But the RP diaphragm is a printed conductor on a thin polymer film suspended in a planar magnetic field — an orthodynamic design, not a moving coil in a gap. The distinction is not academic for choosing a source: a moving-coil driver has a resonant impedance peak in the bass that a high output impedance turns into a tonal shift, while a planar diaphragm presents an essentially flat 50 Ohms across the band, so a high-output-impedance source costs level but not tonal balance. We classify these as planar magnetic for that reason and note the manufacturer's own wording here.
checked 8/5/2026* Estimated with the depreciation fallback (~77% retained value). · checked on 8/5/2026