The Shure AONIC 4 is 7Ω at 106.0 dB/mW; the Shure SE215 is 17Ω at 107.0 dB/mW. This page covers what they ask of an amplifier, not how they sound.
The AONIC 4 needs 1.0 dB more than the SE215 to reach the same loudness — 0.25 mW against 0.20 mW.
| Specification | AONIC 4 | SE215 |
|---|---|---|
| Impedance | 7 Ω | 17 Ω |
| Sensitivity | 106.0 dB/mW | 107.0 dB/mW |
| Sensitivity (voltage) | 127.5 dB/V | 124.7 dB/V |
| Power for 100 dB | 0.25 mW | 0.20 mW |
| Voltage for 100 dB | 42 mV | 58 mV |
| Current for 100 dB | 6.0 mA | 3.4 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 0.88 Ω | 2.12 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.
46 sources are low enough in output impedance for the SE215 under the one-eighth rule but not for the AONIC 4 (FiiO SnowSky Tiny B, FiiO KA13, FiiO BTR15, 43 more).
7 sources stay below the audible-hiss threshold with the SE215 but cross it with the AONIC 4 (Grace Design m900, FiiO M33 R2R, FiiO K17, 4 more).
280 of the 280 sources here reach 100 dB on both.
The SE215 is more demanding than 17% of the 567 non-electrostatic models in this database; the AONIC 4 than 7%.
| dB SPL | AONIC 4 power | AONIC 4 voltage | SE215 power | SE215 voltage |
|---|---|---|---|---|
| 80 | 2.5 µW | 4 mV | 2.0 µW | 6 mV |
| 85 | 7.9 µW | 7 mV | 6.3 µW | 10 mV |
| 90 | 0.03 mW | 13 mV | 0.02 mW | 18 mV |
| 95 | 0.08 mW | 24 mV | 0.06 mW | 33 mV |
| 100 | 0.25 mW | 42 mV | 0.20 mW | 58 mV |
| 105 | 0.79 mW | 75 mV | 0.63 mW | 0.10 V |
| Source | Price | Headroom, AONIC 4 | Headroom, SE215 | Output impedance | Noise |
|---|---|---|---|---|---|
| JadeAudio JA11 | $20 | 14.2 dB | 19.0 dB | 0.5 Ω | 1.7 µV |
| FiiO KA11 | $29 | 26.3 dB | 30.8 dB | 0.7 Ω | 1.7 µV |
| FiiO BTR13 | $59 | 23.2 dB | 27.7 dB | 0.6 Ω | 1.0 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 14.2 dB of headroom on the AONIC 4 and 19.0 dB on the SE215, its output impedance is 0.5 Ω against a one-eighth limit of 0.88 Ω and 2.12 Ω, and its noise figure puts the hiss floor 8 dB and 11 dB below the 20 dB SPL this site treats as the point where a quiet room stops hiding it.
| Model | As printed | Tolerance | Standard |
|---|---|---|---|
| AONIC 4 | 20 Hz –19 kHz | not printed | not printed |
| SE215 | 22 Hz–17.5 kHz | not printed | not printed |
Shure prints 20 Hz –19 kHz for the AONIC 4 and 22 Hz–17.5 kHz for the SE215.
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: Shure AONIC 4 and Shure SE215. Every figure on this page comes from what Shure published, or is derived from it — what that maker publishes, counted.