The HiFiMAN HE5XX (Drop) is 18Ω at 93.5 dB (no reference unit printed); the HiFiMAN Susvara is 60Ω at 83.0 dB (no reference unit printed). This page covers what they ask of an amplifier, not how they sound.
The Susvara needs 10.5 dB more than the HE5XX (Drop) to reach the same loudness — 50 mW against 4.5 mW.
| Specification | HE5XX (Drop) | Susvara |
|---|---|---|
| Impedance | 18 Ω | 60 Ω |
| Sensitivity | 93.5 dB | 83.0 dB |
| Sensitivity (voltage) | 110.9 dB/V | 95.2 dB/V |
| Power for 100 dB | 4.5 mW | 50 mW |
| Voltage for 100 dB | 0.28 V | 1.73 V |
| Current for 100 dB | 15.8 mA | 28.9 mA |
| Highest source impedance that leaves them alone (one-eighth rule) | 2.25 Ω | 7.50 Ω |
| Sources that reach 100 dB out of 280 | 280 | 231 |
One caution before reading the rows. HiFiMAN HE5XX (Drop) and HiFiMAN Susvara 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.
49 of the 280 sources have the power for the HE5XX (Drop) but not for the Susvara — Apple USB-C dongle (US), Apple USB-C dongle (EU), Generic CX31993 dongles, 46 more.
1 source is low enough in output impedance for the Susvara under the one-eighth rule but not for the HE5XX (Drop) (Shanling H5).
231 of the 280 sources here reach 100 dB on both.
The Susvara is more demanding than 99% of the 567 non-electrostatic models in this database; the HE5XX (Drop) than 74%.
| dB SPL | HE5XX (Drop) power | HE5XX (Drop) voltage | Susvara power | Susvara voltage |
|---|---|---|---|---|
| 80 | 0.04 mW | 28 mV | 0.50 mW | 0.17 V |
| 85 | 0.14 mW | 50 mV | 1.6 mW | 0.31 V |
| 90 | 0.45 mW | 90 mV | 5.0 mW | 0.55 V |
| 95 | 1.4 mW | 0.16 V | 16 mW | 0.98 V |
| 100 | 4.5 mW | 0.28 V | 50 mW | 1.73 V |
| 105 | 14 mW | 0.50 V | 158 mW | 3.08 V |
| Source | Price | Headroom, HE5XX (Drop) | Headroom, Susvara | Output impedance | Noise |
|---|---|---|---|---|---|
| FiiO KA11 | $29 | 17.2 dB | 3.3 dB | 0.7 Ω | 1.7 µV |
| FiiO BTR13 | $59 | 14.1 dB | 0.2 dB | 0.6 Ω | 1.0 µV |
| iBasso DC03 Pro | $69 | 10.9 dB | 0.2 dB | 0.12 Ω | 0.9 µV |
Of the 280 sources here, 231 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 17.2 dB of headroom on the HE5XX (Drop) and 3.3 dB on the Susvara, its output impedance is 0.7 Ω against a one-eighth limit of 2.25 Ω and 7.50 Ω, and its noise figure puts the hiss floor 24 dB and 40 dB below the 20 dB SPL this site treats as the point where a quiet room stops hiding it.
| Model | As printed | Tolerance | Standard |
|---|---|---|---|
| HE5XX (Drop) | 20 Hz - 20 kHz | not printed | not printed |
| Susvara | 6Hz-75kHz | not printed | not printed |
HiFiMAN prints 20 Hz - 20 kHz for the HE5XX (Drop) and 6Hz-75kHz for the Susvara.
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 HE5XX (Drop) and HiFiMAN Susvara. 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.