The HarmonicDyne Zeus is 64Ω. The shop listing this figure stands on prints a sensitivity of 100.0 dB and never says whether that is per milliwatt or per volt, so this page reads it as per milliwatt — on that reading it needs 1.0 mW to reach 100 dB SPL, or 0.25 V across the drivers. If the figure is really per volt, it needs far more.
That puts it in the easy category. A phone, a laptop headphone jack or the cheapest USB dongle will drive it to painful levels. Of the 280 sources in the database, 277 have at least 10 dB of headroom and another 3 have enough. The cheapest portable source that does the job is the Apple USB-C dongle (US) at $9.
This maker printed a decibel figure and no reference unit, so the number above is shown exactly as printed. Everything below reads it as per milliwatt, which is the commoner convention on a sheet that omits the unit — if it is really per volt, this headphone is about 12 dB harder to drive than the rest of this page assumes. The converter explains the difference.
HarmonicDyne, as the shop reproduces it, publishes a sensitivity of 100 dB and does not state whether that is per milliwatt or per volt — the spec sheet simply stops at the number.
Both readings are given here so you can judge for yourself. If that 100 dB is per milliwatt, the figures on this page are right as they stand. If it is per volt, the real sensitivity is 88.1 dB/mW — 12 dB lower at 64Ω — and everything above understates what these need by that much. The per-milliwatt reading is the one shown, because it is the more common convention on a spec sheet that omits the unit; treat it as an indication rather than a specification.
One caveat about the source. Almost everything in this database comes from a document the maker published. This entry does not: the figures above stand on someone else's product page — HiFiGo, a retailer and Linsoul, a Chinese-audio retailer — and not on any page HarmonicDyne publishes. Shops usually copy the factory table faithfully and this one may well be exact — but a shop can also carry an old revision, and if HarmonicDyne changes the number there is nothing here that would notice. It is the weakest provenance on this site, which is why it is written on the page rather than left in a footnote.
HarmonicDyne does own a domain, harmonicdyne.com, but it serves a TLS certificate issued for a different name, so no browser that checks certificates will open it. Its product pages cannot be read at all, which is a different thing from a maker that never published: the document may exist and simply be unreachable.
Source: hifigo.com, linsoul.com. How this data was built.
| As it is labelled | As printed | Tolerance | Standard |
|---|---|---|---|
| frequency response | 10Hz to 40kHz | not printed | not printed |
Linsoul, a Chinese-audio retailer, lists 10Hz to 40kHz for the HarmonicDyne Zeus, under the heading “frequency response”. Source: linsoul.com. No document published by HarmonicDyne carries this figure, so it is the shop's number, not the maker's.
The figure is in the shop’s product copy about the driver, not in a specification row.
No tolerance is printed with it, so “10Hz to 40kHz” says nothing about how loud this headphone actually is at 10 Hz.
Only what the maker printed; maker by maker.
| Level | What it is | Power | Voltage | Current |
|---|---|---|---|---|
| 85 dB SPL | quiet background listening | 0.03 mW | 45 mV | 0.7 mA |
| 95 dB SPL | normal listening | 0.32 mW | 0.14 V | 2.2 mA |
| 100 dB SPL | loud listening | 1.0 mW | 0.25 V | 4.0 mA |
| 105 dB SPL | very loud | 3.2 mW | 0.45 V | 7.0 mA |
| 110 dB SPL | peaks on dynamic music | 10 mW | 0.80 V | 12.5 mA |
Most people listen between 75 and 85 dB; the 100 dB row leaves room for peaks.
The 15 cheapest of the 280 sources here that reach 100 dB SPL into 64Ω with at least 10 dB of headroom and no known hiss or output-impedance problem with these headphones. All 280 sources, judged for these headphones.
| Source | Type | Price | Power into 64Ω | Headroom | Verdict |
|---|---|---|---|---|---|
| JadeAudio JA11 | USB dongle | $20 | 15 mW | +12 dB | Comfortable |
| FiiO SnowSky Tiny A | USB dongle | $22 | 17 mW | +12 dB | Comfortable |
| FiiO SnowSky Tiny B | USB dongle | $22 | 17 mW | +12 dB | Comfortable |
| FiiO KA11 | USB dongle | $29 | 100 mW | +20 dB | Comfortable |
| Tanchjim Stargate II | USB dongle | $40 | 38 mW | +16 dB | Comfortable |
| ddHiFi TC35AL | USB dongle | $46 | 105 mW | +20 dB | Comfortable |
| ddHiFi TC35Air | USB dongle | $46 | 105 mW | +20 dB | Comfortable |
| Fosi Audio N3 | Bluetooth receiver | $50 | 69 mW | +18 dB | Comfortable |
| Hidizs SD2 | USB dongle | $50 | 35 mW | +15 dB | Comfortable |
| FiiO BTR13 | Bluetooth receiver | $59 | 50 mW | +17 dB | Comfortable |
| iFi GO link | USB dongle | $59 | 38 mW | +16 dB | Comfortable |
| Kiwi Ears Allegro Pro | USB dongle | $60 | 34 mW | +15 dB | Comfortable |
| ddHiFi TC35Pro (Mountain2) | USB dongle | $66 | 33 mW | +15 dB | Comfortable |
| iBasso DC03 Pro | USB dongle | $69 | 49 mW | +17 dB | Comfortable |
| DUNU DTC 480 | USB dongle | $70 | 33 mW | +15 dB | Comfortable |
Hiss. At 111.9 dB/V these are sensitive enough to reveal a source's own noise floor. The noisiest source in the database, the Schiit Mjolnir 3, would put its hiss at roughly 20 dB SPL in these headphones — clearly audible in quiet passages. Check your own source.
Output impedance. At 64Ω these want a source output impedance below 8.00Ω to satisfy the one-eighth rule; 34 of the 192 sources that publish one miss it. Check yours here.
64Ω · 103.0 dB · Easy
See requirements →64Ω · 100.0 dB/mW · Easy
See requirements →16Ω · 94.0 dB · Easy
See requirements →22Ω · 95.4 dB/mW · Easy
See requirements →20Ω · 95.0 dB/mW · Easy
See requirements →25Ω · 96.0 dB/mW · Easy
See requirements →Compared with its stablemates: vs Poseidon.