On power: 9 of the 13 Bluetooth receivers here reach 100 dB SPL on the HiFiMAN Susvara. It needs 50 mW at its 60Ω, and 4 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 4 that fall short are FiiO BTR11, EarStudio ES100 MK2, FiiO BTR5 2021, HiBy W5. The closest of them, the FiiO BTR5 2021, delivers 43 mW into 60Ω against the 50 mW needed — 0.7 dB short.
The cheapest one that does reach it is the Fosi Audio N3 at $50, which delivers 74 mW into 60Ω — 2 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 7 Bluetooth receivers here that publish an output impedance, 7 are under it and 0 are not.
The other 6 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 6 Bluetooth receivers here that publish a noise figure, 6 stay below that threshold with this headphone and 0 cross it.
The remaining 7 publish no noise figure, so they cannot be placed on either side.
| Source | Price | Into 60 Ω | Headroom | Output impedance | Hiss in these |
|---|---|---|---|---|---|
| FiiO BTR13 | $59 | 53 mW | 0.2 dB | 0.6 Ω | -25 dB SPL |
| FiiO BTR15 | $109 | 68 mW | 1.3 dB | 1.0 Ω | -19 dB SPL |
| FiiO BTR17 | $199 | 149 mW | 4.7 dB | 1.0 Ω | -15 dB SPL |
6 of the 13 Bluetooth receivers here publish all three figures. 4 of those clear all three for the HiFiMAN Susvara, and the cheapest is the FiiO BTR13 at $59.
It delivers 53 mW into 60 Ω where this headphone needs 50 mW for 100 dB — 0.2 dB of headroom — its output impedance of 0.6 Ω sits under the one-eighth ceiling of 7.50 Ω, and its 1.0 µV of noise leaves the hiss 45 dB under the 20 dB SPL threshold this site uses.
Cheapest that satisfies three published numbers is not the same as best, and the sources left out of this count are left out for want of a published figure, not for failing one. How often that happens is its own page.
| Source | Price | Into 60Ω | Output impedance | Hiss in these | Power verdict |
|---|---|---|---|---|---|
| FiiO BTR17 | $199 | 149 mW | 1 Ω | -15 dB SPL | Enough |
| Shanling UP6 | $199 | 334 mW | not published | not published | Enough |
| Fosi Audio N3 | $50 | 74 mW | not published | not published | Marginal |
| FiiO BTR13 | $59 | 53 mW | 0.6 Ω | -25 dB SPL | Marginal |
| FiiO BTR15 | $109 | 68 mW | 1 Ω | -19 dB SPL | Marginal |
| Qudelix 5K | $109 | 67 mW | not published | not published | Marginal |
| Shanling UP5 | $179 | 60 mW | not published | not published | Marginal |
| FiiO BTR7 | $199 | 86 mW | 1.2 Ω | -15 dB SPL | Marginal |
| iFi GO blu | $219 | 88 mW | 1 Ω | not published | Marginal |
| FiiO BTR11 | $36 | 16 mW | 0.5 Ω | -7 dB SPL | Not enough |
| EarStudio ES100 MK2 | $90 | 36 mW | not published | not published | Not enough |
| FiiO BTR5 2021 | $109 | 43 mW | 1 Ω | -19 dB SPL | Not enough |
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: USB dongles · 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.