The HiFiMAN HE-R9 is 60Ω at 100.0 dB (no reference unit printed); the HiFiMAN HE6 Remastered is 50Ω at 83.5 dB (no reference unit printed). This page covers what they ask of an amplifier, not how they sound.
The HE6 Remastered needs 16.5 dB more than the HE-R9 to reach the same loudness — 45 mW against 1.0 mW.
| Specification | HE-R9 | HE6 Remastered |
|---|---|---|
| Impedance | 60 Ω | 50 Ω |
| Sensitivity | 100.0 dB | 83.5 dB |
| Sensitivity (voltage) | 112.2 dB/V | 96.5 dB/V |
| Power for 100 dB | 1.0 mW | 45 mW |
| Voltage for 100 dB | 0.24 V | 1.49 V |
| Current for 100 dB | 4.1 mA | 29.9 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 7.50 Ω | 6.25 Ω |
| Sources that reach 100 dB out of 280 | 280 | 240 |
One caution before reading the rows. HiFiMAN HE-R9 and HiFiMAN HE6 Remastered printed a decibel figure with no reference unit, so this page reads it as per milliwatt. If it is really per volt, each of them needs far more than the table says. Why the two readings differ by so much.
40 of the 280 sources have the power for the HE-R9 but not for the HE6 Remastered — Apple USB-C dongle (US), Apple USB-C dongle (EU), Generic CX31993 dongles, 37 more.
1 source stays below the audible-hiss threshold with the HE6 Remastered but crosses it with the HE-R9 (Schiit Mjolnir 3).
240 of the 280 sources here reach 100 dB on both.
The HE6 Remastered is more demanding than 99% of the 567 non-electrostatic models in this database; the HE-R9 than 66%.
| dB SPL | HE-R9 power | HE-R9 voltage | HE6 Remastered power | HE6 Remastered voltage |
|---|---|---|---|---|
| 80 | 0.01 mW | 24 mV | 0.45 mW | 0.15 V |
| 85 | 0.03 mW | 44 mV | 1.4 mW | 0.27 V |
| 90 | 0.10 mW | 77 mV | 4.5 mW | 0.47 V |
| 95 | 0.32 mW | 0.14 V | 14 mW | 0.84 V |
| 100 | 1.0 mW | 0.24 V | 45 mW | 1.49 V |
| 105 | 3.2 mW | 0.44 V | 141 mW | 2.66 V |
| Source | Price | Headroom, HE-R9 | Headroom, HE6 Remastered | Output impedance | Noise |
|---|---|---|---|---|---|
| FiiO KA11 | $29 | 20.3 dB | 4.6 dB | 0.7 Ω | 1.7 µV |
| FiiO BTR13 | $59 | 17.2 dB | 1.5 dB | 0.6 Ω | 1.0 µV |
| iBasso DC03 Pro | $69 | 17.2 dB | 1.5 dB | 0.12 Ω | 0.9 µV |
Of the 280 sources here, 240 reach 100 dB on both. 66 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 66 is the FiiO KA11, at $29. It leaves 20.3 dB of headroom on the HE-R9 and 4.6 dB on the HE6 Remastered, its output impedance is 0.7 Ω against a one-eighth limit of 7.50 Ω and 6.25 Ω, and its noise figure puts the hiss floor 23 dB and 39 dB below the 20 dB SPL this site treats as the point where a quiet room stops hiding it.
| Model | As printed | Tolerance | Standard |
|---|---|---|---|
| HE-R9 | 15Hz-35kHz | not printed | not printed |
| HE6 Remastered | 8 Hz - 65 kHz | not printed | not printed |
HiFiMAN prints 15Hz-35kHz for the HE-R9 and 8 Hz - 65 kHz for the HE6 Remastered.
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: HiFiMAN HE-R9 and HiFiMAN HE6 Remastered. Each figure on this page is labelled on those pages with where it came from, including the ones HiFiMAN never published — what that maker publishes, counted.