The Sennheiser IE 500 PRO is 16Ω at 108.0 dB/mW; the Sennheiser IE 900 is 16Ω at 105.0 dB/mW. This page covers what they ask of an amplifier, not how they sound.
The IE 900 needs 3.0 dB more than the IE 500 PRO to reach the same loudness — 0.32 mW against 0.16 mW.
| Specification | IE 500 PRO | IE 900 |
|---|---|---|
| Impedance | 16 Ω | 16 Ω |
| Sensitivity | 108.0 dB/mW | 105.0 dB/mW |
| Sensitivity (voltage) | 126.0 dB/V | 123.0 dB/V |
| Power for 100 dB | 0.16 mW | 0.32 mW |
| Voltage for 100 dB | 50 mV | 71 mV |
| Current for 100 dB | 3.1 mA | 4.4 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 2.00 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.
11 sources stay below the audible-hiss threshold with the IE 900 but cross it with the IE 500 PRO (Lake People G103-S Mk II, Schiit Valhalla 3, Lake People G111 Mk II, 8 more).
280 of the 280 sources here reach 100 dB on both.
The IE 900 is more demanding than 22% of the 567 non-electrostatic models in this database; the IE 500 PRO than 11%.
| dB SPL | IE 500 PRO power | IE 500 PRO voltage | IE 900 power | IE 900 voltage |
|---|---|---|---|---|
| 80 | 1.6 µW | 5 mV | 3.2 µW | 7 mV |
| 85 | 5.0 µW | 9 mV | 0.01 mW | 13 mV |
| 90 | 0.02 mW | 16 mV | 0.03 mW | 22 mV |
| 95 | 0.05 mW | 28 mV | 0.10 mW | 40 mV |
| 100 | 0.16 mW | 50 mV | 0.32 mW | 71 mV |
| 105 | 0.50 mW | 90 mV | 1.0 mW | 0.13 V |
| Source | Price | Headroom, IE 500 PRO | Headroom, IE 900 | Output impedance | Noise |
|---|---|---|---|---|---|
| JadeAudio JA11 | $20 | 19.8 dB | 16.8 dB | 0.5 Ω | 1.7 µV |
| FiiO KA11 | $29 | 31.9 dB | 28.9 dB | 0.7 Ω | 1.7 µV |
| FiiO BTR13 | $59 | 28.8 dB | 25.8 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 19.8 dB of headroom on the IE 500 PRO and 16.8 dB on the IE 900, its output impedance is 0.5 Ω against a one-eighth limit of 2.00 Ω for both, and its noise figure puts the hiss floor 9 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 |
|---|---|---|---|
| IE 500 PRO | 6 – 20,000 Hz | not printed | not printed |
| IE 900 | 5 Hz – 48,000 Hz | not printed | not printed |
Sennheiser prints 6 – 20,000 Hz for the IE 500 PRO and 5 Hz – 48,000 Hz for the IE 900.
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 500 PRO and Sennheiser IE 900. Every figure on this page comes from what Sennheiser published, or is derived from it — what that maker publishes, counted.