The Sennheiser IE 100 PRO is 20Ω at 98.0 dB/mW; the Sennheiser IE 500 PRO is 16Ω at 108.0 dB/mW. This page covers what they ask of an amplifier, not how they sound.
The IE 100 PRO needs 10.0 dB more than the IE 500 PRO to reach the same loudness — 1.6 mW against 0.16 mW.
| Specification | IE 100 PRO | IE 500 PRO |
|---|---|---|
| Impedance | 20 Ω | 16 Ω |
| Sensitivity | 98.0 dB/mW | 108.0 dB/mW |
| Sensitivity (voltage) | 115.0 dB/V | 126.0 dB/V |
| Power for 100 dB | 1.6 mW | 0.16 mW |
| Voltage for 100 dB | 0.18 V | 50 mV |
| Current for 100 dB | 8.9 mA | 3.1 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 2.50 Ω | 2.00 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.
14 sources stay below the audible-hiss threshold with the IE 100 PRO but cross it with the IE 500 PRO (FiiO BTR11, FiiO K11 R2R, Lake People G103-S Mk II, 11 more).
280 of the 280 sources here reach 100 dB on both.
The IE 100 PRO is more demanding than 52% of the 567 non-electrostatic models in this database; the IE 500 PRO than 11%.
| dB SPL | IE 100 PRO power | IE 100 PRO voltage | IE 500 PRO power | IE 500 PRO voltage |
|---|---|---|---|---|
| 80 | 0.02 mW | 18 mV | 1.6 µW | 5 mV |
| 85 | 0.05 mW | 32 mV | 5.0 µW | 9 mV |
| 90 | 0.16 mW | 56 mV | 0.02 mW | 16 mV |
| 95 | 0.50 mW | 0.10 V | 0.05 mW | 28 mV |
| 100 | 1.6 mW | 0.18 V | 0.16 mW | 50 mV |
| 105 | 5.0 mW | 0.32 V | 0.50 mW | 90 mV |
| Source | Price | Headroom, IE 100 PRO | Headroom, IE 500 PRO | Output impedance | Noise |
|---|---|---|---|---|---|
| JadeAudio JA11 | $20 | 10.7 dB | 19.8 dB | 0.5 Ω | 1.7 µV |
| FiiO KA11 | $29 | 21.5 dB | 31.9 dB | 0.7 Ω | 1.7 µV |
| FiiO BTR13 | $59 | 18.4 dB | 28.8 dB | 0.6 Ω | 1.0 µV |
Of the 280 sources here, 280 reach 100 dB on both. 57 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 57 is the JadeAudio JA11, at $20. It leaves 10.7 dB of headroom on the IE 100 PRO and 19.8 dB on the IE 500 PRO, its output impedance is 0.5 Ω against a one-eighth limit of 2.50 Ω and 2.00 Ω, and its noise figure puts the hiss floor 20 dB and 9 dB below the 20 dB SPL this site treats as the point where a quiet room stops hiding it.
| Model | As printed | Tolerance | Standard |
|---|---|---|---|
| IE 100 PRO | 20 - 18,000 Hz | not printed | not printed |
| IE 500 PRO | 6 – 20,000 Hz | not printed | not printed |
Sennheiser prints 20 - 18,000 Hz for the IE 100 PRO and 6 – 20,000 Hz for the IE 500 PRO.
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: Sennheiser IE 100 PRO and Sennheiser IE 500 PRO. Every figure on this page comes from what Sennheiser published, or is derived from it — what that maker publishes, counted.