The 64 Audio Fourte is 10Ω at 114.0 dB/mW; the 64 Audio Ocean is 9.5Ω at 103.7 dB/mW. This page covers what they ask of an amplifier, not how they sound.
The Ocean needs 10.3 dB more than the Fourte to reach the same loudness — 0.43 mW against 0.04 mW.
| Specification | Fourte | Ocean |
|---|---|---|
| Impedance | 10 Ω | 9.5 Ω |
| Sensitivity | 114.0 dB/mW | 103.7 dB/mW |
| Sensitivity (voltage) | 134.0 dB/V | 123.9 dB/V |
| Power for 100 dB | 0.04 mW | 0.43 mW |
| Voltage for 100 dB | 20 mV | 64 mV |
| Current for 100 dB | 2.0 mA | 6.7 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 1.25 Ω | 1.19 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.
3 sources are low enough in output impedance for the Fourte under the one-eighth rule but not for the Ocean (FiiO K11, FiiO BTR7, FiiO Q7).
42 sources stay below the audible-hiss threshold with the Ocean but cross it with the Fourte (Kiwi Ears Allegro Mini, FiiO KA13, Fosi Audio SK02, 39 more).
280 of the 280 sources here reach 100 dB on both.
The Ocean is more demanding than 19% of the 567 non-electrostatic models in this database; the Fourte than 1%.
| dB SPL | Fourte power | Fourte voltage | Ocean power | Ocean voltage |
|---|---|---|---|---|
| 80 | 0.4 µW | 2 mV | 4.3 µW | 6 mV |
| 85 | 1.3 µW | 4 mV | 0.01 mW | 11 mV |
| 90 | 4.0 µW | 6 mV | 0.04 mW | 20 mV |
| 95 | 0.01 mW | 11 mV | 0.13 mW | 36 mV |
| 100 | 0.04 mW | 20 mV | 0.43 mW | 64 mV |
| 105 | 0.13 mW | 35 mV | 1.3 mW | 0.11 V |
| Source | Price | Headroom, Fourte | Headroom, Ocean | Output impedance | Noise |
|---|---|---|---|---|---|
| JadeAudio JA11 | $20 | 23.7 dB | 13.2 dB | 0.5 Ω | 1.7 µV |
| FiiO KA11 | $29 | 35.9 dB | 25.3 dB | 0.7 Ω | 1.7 µV |
| FiiO BTR13 | $59 | 32.8 dB | 22.2 dB | 0.6 Ω | 1.0 µV |
Of the 280 sources here, 280 reach 100 dB on both. 26 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 26 is the JadeAudio JA11, at $20. It leaves 23.7 dB of headroom on the Fourte and 13.2 dB on the Ocean, its output impedance is 0.5 Ω against a one-eighth limit of 1.25 Ω and 1.19 Ω, and its noise figure puts the hiss floor 1 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 |
|---|---|---|---|
| Fourte | 5hz – 22kHz | not printed | not printed |
| Ocean | 5 Hz – 22 kHz | not printed | not printed |
64 Audio prints 5hz – 22kHz for the Fourte and 5 Hz – 22 kHz for the Ocean.
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: 64 Audio Fourte and 64 Audio Ocean. Every figure on this page comes from what 64 Audio published, or is derived from it — what that maker publishes, counted.