On power: 34 of the 51 USB dongles here reach 100 dB SPL on the HiFiMAN Susvara. It needs 50 mW at its 60Ω, and 17 of them do not get there.
Power is one of three questions and the one that goes wrong least often. The other two — whether the source’s output impedance leaves the frequency response alone, and whether you will hear its noise floor — are answered further down, separately, because a source can pass one and fail another.
The 17 that fall short are Apple USB-C dongle (US), Apple USB-C dongle (EU), Generic CX31993 dongles, JadeAudio JA11, 13 more. The closest of them, the ddHiFi TC44Grip, delivers 43 mW into 60Ω against the 50 mW needed — 0.7 dB short.
The cheapest one that does reach it is the FiiO KA11 at $29, which delivers 107 mW into 60Ω — 3 dB of headroom over the 50 mW this headphone needs for 100 dB SPL.
100 dB SPL is a peak level, not a listening level. If you listen at 85 dB the same headphone needs 1.6 mW, which is 15 dB less, and the answer above changes for most of the category. The model page has the full ladder.
Under the one-eighth rule the HiFiMAN Susvara wants a source below 7.50Ω. Of the 18 USB dongles here that publish an output impedance, 18 are under it and 0 are not.
The other 33 publish nothing at all on this, so they are not on either side of that count. This site leaves them blank rather than assuming a figure.
Hiss depends on the source’s own noise floor and on how sensitive the headphone is. At 83.0 dB and 60Ω, the HiFiMAN Susvara turns one microvolt of source noise into about -25 dB SPL — and the threshold where that stops being noticeable in a quiet room is around 20 dB SPL.
Of the 16 USB dongles here that publish a noise figure, 16 stay below that threshold with this headphone and 0 cross it.
The remaining 35 publish no noise figure, so they cannot be placed on either side.
| Source | Price | Into 60Ω | Output impedance | Hiss in these | Power verdict |
|---|---|---|---|---|---|
| FiiO KA11 | $29 | 107 mW | 0.7 Ω | -20 dB SPL | Enough |
| ddHiFi TC35AL | $46 | 112 mW | not published | not published | Enough |
| ddHiFi TC35Air | $46 | 112 mW | not published | not published | Enough |
| Tempotec Sonata BHD Pro | $60 | 149 mW | not published | not published | Enough |
| ddHiFi TC44 Pro E2 | $99 | 133 mW | not published | not published | Enough |
| Tanchjim LUNA | $140 | 163 mW | not published | -23 dB SPL | Enough |
| Moondrop Moonriver 2 Ti | $190 | 160 mW | not published | -21 dB SPL | Enough |
| Qudelix T71 | $229 | 267 mW | not published | not published | Enough |
| Questyle M15 | $250 | 184 mW | not published | not published | Enough |
| iBasso DC03 Pro | $69 | 52 mW | 0.12 Ω | -26 dB SPL | Marginal |
| EPZ TP35 Pro | $70 | 60 mW | not published | not published | Marginal |
| Tanchjim Space | $70 | 67 mW | not published | -24 dB SPL | Marginal |
Sorted by how many of the three questions the source answers well, then by price. A blank in a column is a blank in the manufacturer’s own documentation, not a zero.
The HiFiMAN Susvara on other categories: Bluetooth receivers · portable players · desktop amplifiers · desktop DAC/amps · audio interfaces.
The HiFiMAN Susvara page has every source in the database against this headphone, and the matcher takes your own numbers.