The Softears RSV is 8Ω at 104.0 dB/mW; the Softears Volume is 5Ω at 100.7 dB/mW. This page covers what they ask of an amplifier, not how they sound.
The Volume needs 3.3 dB more than the RSV to reach the same loudness — 0.85 mW against 0.40 mW.
| Specification | RSV | Volume |
|---|---|---|
| Impedance | 8 Ω | 5 Ω |
| Sensitivity | 104.0 dB/mW | 100.7 dB/mW |
| Sensitivity (voltage) | 125.0 dB/V | 123.7 dB/V |
| Power for 100 dB | 0.40 mW | 0.85 mW |
| Voltage for 100 dB | 56 mV | 65 mV |
| Current for 100 dB | 7.1 mA | 13.0 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 1.00 Ω | 0.62 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.
42 sources are low enough in output impedance for the RSV under the one-eighth rule but not for the Volume (FiiO SnowSky Tiny B, FiiO KA11, JDS Labs Atom+ (2nd gen), 39 more).
5 sources stay below the audible-hiss threshold with the Volume but cross it with the RSV (Lake People G103-S Mk II, Schiit Valhalla 3, RME Babyface Pro FS, 2 more).
280 of the 280 sources here reach 100 dB on both.
The Volume is more demanding than 20% of the 567 non-electrostatic models in this database; the RSV than 14%.
| dB SPL | RSV power | RSV voltage | Volume power | Volume voltage |
|---|---|---|---|---|
| 80 | 4.0 µW | 6 mV | 8.5 µW | 7 mV |
| 85 | 0.01 mW | 10 mV | 0.03 mW | 12 mV |
| 90 | 0.04 mW | 18 mV | 0.09 mW | 21 mV |
| 95 | 0.13 mW | 32 mV | 0.27 mW | 37 mV |
| 100 | 0.40 mW | 56 mV | 0.85 mW | 65 mV |
| 105 | 1.3 mW | 0.10 V | 2.7 mW | 0.12 V |
| Source | Price | Headroom, RSV | Headroom, Volume | Output impedance | Noise |
|---|---|---|---|---|---|
| JadeAudio JA11 | $20 | 12.8 dB | 7.4 dB | 0.5 Ω | 1.7 µV |
| FiiO BTR13 | $59 | 21.8 dB | 16.4 dB | 0.6 Ω | 1.0 µV |
| iBasso DC03 Pro | $69 | 17.9 dB | 12.6 dB | 0.12 Ω | 0.9 µV |
Of the 280 sources here, 280 reach 100 dB on both. 33 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 33 is the JadeAudio JA11, at $20. It leaves 12.8 dB of headroom on the RSV and 7.4 dB on the Volume, its output impedance is 0.5 Ω against a one-eighth limit of 1.00 Ω and 0.62 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 | |
| Volume | 8- 40kHz(1/4 inch free field microphone, -5 dB) | -5 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, “8- 40kHz(1/4 inch free field microphone, -5 dB)” and “20- 20kHz (IEC60318-4)”, for the Volume.
Volume: The tolerance Softears prints is −5 dB — a looser one than the −3 dB almost everyone else uses, and one that makes the range wider than it would otherwise be.
Only one of the two is a specification. The range printed for the Volume 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 Volume. Every figure on this page comes from what Softears published, or is derived from it — what that maker publishes, counted.