The Softears RSV is 8Ω at 104.0 dB/mW; the Softears Studio4 is 12Ω at 103.8 dB/mW. This page covers what they ask of an amplifier, not how they sound.
In amplifier terms these two are the same headphone. The gap between what they need for 100 dB is under half a decibel, which is smaller than the step between two clicks of most volume controls.
| Specification | RSV | Studio4 |
|---|---|---|
| Impedance | 8 Ω | 12 Ω |
| Sensitivity | 104.0 dB/mW | 103.8 dB/mW |
| Sensitivity (voltage) | 125.0 dB/V | 123.0 dB/V |
| Power for 100 dB | 0.40 mW | 0.42 mW |
| Voltage for 100 dB | 56 mV | 71 mV |
| Current for 100 dB | 7.1 mA | 5.9 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 1.00 Ω | 1.50 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.
7 sources are low enough in output impedance for the Studio4 under the one-eighth rule but not for the RSV (FiiO K11, FiiO BTR7, FiiO M11S, 4 more).
6 sources stay below the audible-hiss threshold with the Studio4 but cross it with the RSV (Lake People G103-S Mk II, Schiit Valhalla 3, Lake People G111 Mk II, 3 more).
280 of the 280 sources here reach 100 dB on both.
The Studio4 is more demanding than 21% of the 567 non-electrostatic models in this database; the RSV than 14%.
| dB SPL | RSV power | RSV voltage | Studio4 power | Studio4 voltage |
|---|---|---|---|---|
| 80 | 4.0 µW | 6 mV | 4.2 µW | 7 mV |
| 85 | 0.01 mW | 10 mV | 0.01 mW | 13 mV |
| 90 | 0.04 mW | 18 mV | 0.04 mW | 22 mV |
| 95 | 0.13 mW | 32 mV | 0.13 mW | 40 mV |
| 100 | 0.40 mW | 56 mV | 0.42 mW | 71 mV |
| 105 | 1.3 mW | 0.10 V | 1.3 mW | 0.13 V |
| Source | Price | Headroom, RSV | Headroom, Studio4 | Output impedance | Noise |
|---|---|---|---|---|---|
| JadeAudio JA11 | $20 | 12.8 dB | 14.3 dB | 0.5 Ω | 1.7 µV |
| FiiO KA11 | $29 | 24.9 dB | 26.4 dB | 0.7 Ω | 1.7 µV |
| FiiO BTR13 | $59 | 21.8 dB | 23.3 dB | 0.6 Ω | 1.0 µV |
Of the 280 sources here, 280 reach 100 dB on both. 55 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 55 is the JadeAudio JA11, at $20. It leaves 12.8 dB of headroom on the RSV and 14.3 dB on the Studio4, its output impedance is 0.5 Ω against a one-eighth limit of 1.00 Ω and 1.50 Ω, and its noise figure puts the hiss floor 10 dB and 12 dB below the 20 dB SPL this site treats as the point where a quiet room stops hiding it.
| Model | As printed | Tolerance | Standard |
|---|---|---|---|
| RSV | 5-40kHz | not printed | not printed |
| 20-20kHz | not printed | not printed | |
| Studio4 | 5-40kHz (1/4' free field, -3Db) | -3 dB | 1/4″ free field |
| 20-20kHz (IEC60318-4) | not printed | IEC60318-4 |
Softears prints two ranges, “5-40kHz” and “20-20kHz”, for the RSV and two ranges, “5-40kHz (1/4' free field, -3Db)” and “20-20kHz (IEC60318-4)”, for the Studio4.
Studio4: Softears puts the tolerance on the WIDE range and leaves the effective one without it — the opposite way round to every other maker here that prints both.
Only one of the two is a specification. The range printed for the Studio4 comes with a tolerance; the one printed for the RSV does not, and a range without a ±dB figure says nothing about how loud that model is at either end of it. The two cannot be compared number against number, however similar they look in the table. Of the 490 models whose maker prints a range, 58 print the tolerance.
Not a measurement; maker by maker.
Both have a page of their own. In full: Softears RSV and Softears Studio4. Every figure on this page comes from what Softears published, or is derived from it — what that maker publishes, counted.