The Fostex T20RP MK3 is 50Ω at 92.0 dB/mW; the Fostex T60RPmk2 is 28Ω at 96.0 dB/mW. This page covers what they ask of an amplifier, not how they sound.
The T20RP MK3 needs 4.0 dB more than the T60RPmk2 to reach the same loudness — 6.3 mW against 2.5 mW.
| Specification | T20RP MK3 | T60RPmk2 |
|---|---|---|
| Impedance | 50 Ω | 28 Ω |
| Sensitivity | 92.0 dB/mW | 96.0 dB/mW |
| Sensitivity (voltage) | 105.0 dB/V | 111.5 dB/V |
| Power for 100 dB | 6.3 mW | 2.5 mW |
| Voltage for 100 dB | 0.56 V | 0.27 V |
| Current for 100 dB | 11.2 mA | 9.5 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 6.25 Ω | 3.50 Ω |
| Sources that reach 100 dB out of 280 | 280 | 280 |
Every source in the database that drives one of them drives the other. On power, the choice between these two changes nothing about what amplifier you need.
1 source is low enough in output impedance for the T20RP MK3 under the one-eighth rule but not for the T60RPmk2 (Shanling H5).
280 of the 280 sources here reach 100 dB on both.
The T20RP MK3 is more demanding than 88% of the 567 non-electrostatic models in this database; the T60RPmk2 than 69%.
| dB SPL | T20RP MK3 power | T20RP MK3 voltage | T60RPmk2 power | T60RPmk2 voltage |
|---|---|---|---|---|
| 80 | 0.06 mW | 56 mV | 0.03 mW | 27 mV |
| 85 | 0.20 mW | 100 mV | 0.08 mW | 47 mV |
| 90 | 0.63 mW | 0.18 V | 0.25 mW | 84 mV |
| 95 | 2.0 mW | 0.32 V | 0.79 mW | 0.15 V |
| 100 | 6.3 mW | 0.56 V | 2.5 mW | 0.27 V |
| 105 | 20 mW | 1.00 V | 7.9 mW | 0.47 V |
| Source | Price | Headroom, T20RP MK3 | Headroom, T60RPmk2 | Output impedance | Noise |
|---|---|---|---|---|---|
| JadeAudio JA11 | $20 | 4.8 dB | 10.2 dB | 0.5 Ω | 1.7 µV |
| FiiO KA11 | $29 | 13.1 dB | 19.1 dB | 0.7 Ω | 1.7 µV |
| FiiO BTR11 | $36 | 4.8 dB | 11.1 dB | 0.5 Ω | 8.0 µV |
Of the 280 sources here, 280 reach 100 dB on both. 70 of them also publish an output impedance low enough for both under the one-eighth rule and a noise figure that stays below the audible-hiss threshold with both.
The cheapest of the 70 is the JadeAudio JA11, at $20. It leaves 4.8 dB of headroom on the T20RP MK3 and 10.2 dB on the T60RPmk2, its output impedance is 0.5 Ω against a one-eighth limit of 6.25 Ω and 3.50 Ω, and its noise figure puts the hiss floor 30 dB and 24 dB below the 20 dB SPL this site treats as the point where a quiet room stops hiding it.
| Model | As printed | Tolerance | Standard |
|---|---|---|---|
| T20RP MK3 | 15 to 35,000 Hz | not printed | not printed |
| T60RPmk2 | 10～40,000 Hz | not printed | not printed |
Fostex prints 15 to 35,000 Hz for the T20RP MK3 and 10～40,000 Hz for the T60RPmk2.
Neither range has a tolerance printed beside it, so a wider range on one sheet is not deeper bass or more treble.
Not a measurement; maker by maker.
Both have a page of their own. In full: Fostex T20RP MK3 and Fostex T60RPmk2. Every figure on this page comes from what Fostex published, or is derived from it — what that maker publishes, counted.