Short answer
Both are dongles, $149 against $140.
The Tanchjim LUNA reaches 100 dB on 565 of the 567 models here, the FiiO KA17 on 564.
| Specification | FiiO KA17 | Tanchjim LUNA |
|---|---|---|
| Power into 32Ω | 140 mW | 285 mW |
| Power into 150Ω | 34 mW | 80 mW |
| Power into 300Ω | 20 mW | 54 mW |
| Power into 600Ω | 10.0 mW | 27 mW |
| Output impedance | 1.0 Ω | not published |
| Output noise | 2.0 µV | 1.3 µV |
| Price | $149 | $140 |
| Headphones it reaches 100 dB on out of 567 | 564 | 565 |
Not published means the maker leaves it out, so that axis cannot be compared.
| Balanced | FiiO KA17 | Tanchjim LUNA |
|---|---|---|
| Socket | 4.4mm | no separate rating |
| Power into 32Ω | 300 mW | — |
| Power into 300Ω | 30 mW | — |
| Output impedance | 1.5 Ω | — |
| Output noise | 2.2 µV | — |
| Headphones it reaches 100 dB on out of 567 | 565 | — |
Only the FiiO KA17 has a separate balanced rating from its maker; through it, it reaches 100 dB on 565 of the 567 models here. The Tanchjim LUNA may still have a balanced socket — its spec sheet simply gives no figure for one, so there is nothing to put beside it.
| Load | FiiO KA17 | Tanchjim LUNA |
|---|---|---|
| 32 Ω | Published | Published |
| 150 Ω | Derived | Derived |
| 300 Ω | Published | Published |
| 600 Ω | Derived | Derived |
Both makers publish a power rating. FiiO KA17 publishes at 32 Ω and at 300 Ω; Tanchjim LUNA at 32 Ω and at 300 Ω. The other rows are worked out from those.
The two publish at the same loads, which is the one case where the rows of this table can be read straight across.
1 headphone reaches 100 dB on the Tanchjim LUNA but not on the FiiO KA17 — Symphonium Crimson.
5 headphones stay below the audible-hiss threshold on the Tanchjim LUNA but cross it on the FiiO KA17 (64 Audio Fourte, Campfire Audio Clara, Shure SE846, 2 more).
564 of the 567 models here reach 100 dB on both.
Headroom is at a 100 dB SPL peak.
The widest gap on the list is the Sennheiser HD 600: Tanchjim LUNA has +9 dB of headroom there against +5 dB. 4 dB is about 2.7 times the power, which matters for peaks rather than for how loud the music sits.
Hiss below about 20 dB SPL is inaudible in a quiet room.
| Headphone | Impedance | Needs | FiiO KA17 headroom | Tanchjim LUNA headroom | FiiO KA17 hiss | Tanchjim LUNA hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +32 dB | +34 dB | 20 dB | 17 dB |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +12 dB | +14 dB | 0 dB | -3 dB |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +19 dB | +23 dB | -1 dB | -5 dB |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +16 dB | +20 dB | -6 dB | -10 dB |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +12 dB | +15 dB | -7 dB | -11 dB |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +9 dB | +13 dB | -13 dB | -16 dB |
| Sennheiser HD 600 | 300 Ω | 6.6 mW | +5 dB | +9 dB | -17 dB | -21 dB |
| HiFiMAN Susvara | 60 Ω | 50 mW | +2 dB | +5 dB | -19 dB | -23 dB |
The FiiO KA17 costs $9 more than the Tanchjim LUNA, and on these three axes the money buys nothing: among the 567 models here there is not one that the FiiO KA17 handles and the Tanchjim LUNA does not — not on power, not on the one-eighth rule, not on hiss. The traffic runs the other way: the cheaper Tanchjim LUNA drives one model to 100 dB and keeps 5 below the audible-hiss threshold that the FiiO KA17 does not.
Only published figures count here; blank axes are counted separately.
Each in full: FiiO KA17 and Tanchjim LUNA.