The Sennheiser IE 300 is 16Ω at 106.0 dB/mW; the Sennheiser IE 400 PRO is 16Ω at 105.0 dB/mW. This page covers what they ask of an amplifier, not how they sound.
The IE 400 PRO needs 1.0 dB more than the IE 300 to reach the same loudness — 0.32 mW against 0.25 mW.
| Specification | IE 300 | IE 400 PRO |
|---|---|---|
| Impedance | 16 Ω | 16 Ω |
| Sensitivity | 106.0 dB/mW | 105.0 dB/mW |
| Sensitivity (voltage) | 124.0 dB/V | 123.0 dB/V |
| Power for 100 dB | 0.25 mW | 0.32 mW |
| Voltage for 100 dB | 63 mV | 71 mV |
| Current for 100 dB | 4.0 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.
1 source stays below the audible-hiss threshold with the IE 400 PRO but crosses it with the IE 300 (Lake People G111 Mk II).
280 of the 280 sources here reach 100 dB on both.
The IE 400 PRO is more demanding than 22% of the 567 non-electrostatic models in this database; the IE 300 than 18%.
| dB SPL | IE 300 power | IE 300 voltage | IE 400 PRO power | IE 400 PRO voltage |
|---|---|---|---|---|
| 80 | 2.5 µW | 6 mV | 3.2 µW | 7 mV |
| 85 | 7.9 µW | 11 mV | 0.01 mW | 13 mV |
| 90 | 0.03 mW | 20 mV | 0.03 mW | 22 mV |
| 95 | 0.08 mW | 36 mV | 0.10 mW | 40 mV |
| 100 | 0.25 mW | 63 mV | 0.32 mW | 71 mV |
| 105 | 0.79 mW | 0.11 V | 1.0 mW | 0.13 V |
| Source | Price | Headroom, IE 300 | Headroom, IE 400 PRO | Output impedance | Noise |
|---|---|---|---|---|---|
| JadeAudio JA11 | $20 | 17.8 dB | 16.8 dB | 0.5 Ω | 1.7 µV |
| FiiO KA11 | $29 | 29.9 dB | 28.9 dB | 0.7 Ω | 1.7 µV |
| FiiO BTR13 | $59 | 26.8 dB | 25.8 dB | 0.6 Ω | 1.0 µV |
Of the 280 sources here, 280 reach 100 dB on both. 65 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 65 is the JadeAudio JA11, at $20. It leaves 17.8 dB of headroom on the IE 300 and 16.8 dB on the IE 400 PRO, 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 11 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 300 | 6 Hz - 20,000 Hz | not printed | not printed |
| IE 400 PRO | 6 - 19,000 Hz | not printed | not printed |
Sennheiser prints 6 Hz - 20,000 Hz for the IE 300 and 6 - 19,000 Hz for the IE 400 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 300 and Sennheiser IE 400 PRO. Every figure on this page comes from what Sennheiser published, or is derived from it — what that maker publishes, counted.