Short answer
Both are dongles, $149 against $99.
The FiiO KA5 reaches 100 dB on 565 of the 567 models here, the FiiO KA17 on 564.
| Specification | FiiO KA17 | FiiO KA5 |
|---|---|---|
| Power into 32Ω | 140 mW | 122 mW |
| Power into 150Ω | 34 mW | 26 mW |
| Power into 300Ω | 20 mW | 14 mW |
| Power into 600Ω | 10.0 mW | 6.8 mW |
| Output impedance | 1.0 Ω | 0.3 Ω |
| Output noise | 2.0 µV | 1.6 µV |
| Price | $149 | $99 |
| Headphones it reaches 100 dB on out of 567 | 564 | 565 |
| Balanced | FiiO KA17 | FiiO KA5 |
|---|---|---|
| Socket | 4.4mm | 4.4mm |
| Power into 32Ω | 300 mW | 265 mW |
| Power into 300Ω | 30 mW | 54 mW |
| Output impedance | 1.5 Ω | 0.35 Ω |
| Output noise | 2.2 µV | 1.8 µV |
| Headphones it reaches 100 dB on out of 567 | 565 | 565 |
Through the balanced sockets the two are level on the same test: each reaches 100 dB on 565 of the 567 models here.
| As published | FiiO KA17 | FiiO KA5 |
|---|---|---|
| DAC | ES9069Q x2 (USB: XMOS XU316) | CS43198 x2 |
| Outputs | 3.5 mm (PO/coaxial out shared), 4.4 mm balanced | 3.5 mm SE (shared with S/PDIF out), 4.4 mm balanced |
| Connection | USB-C (data/power) + separate USB-C POWER IN port | USB-C |
| Formats | PCM 768 kHz/32-bit, DSD512 native (DoP256); S/PDIF 96 kHz/24-bit | PCM 768 kHz/32-bit, DSD64/128/256 |
| Weight | 33.5 g | 19 g |
| Dimensions | About 64 x 27.7 x 12.7 mm | About 56.3 x 22 x 12 mm |
Copied from the makers’ own pages: fiio.com/KA17_parameters, fiio.com/ka5_parameters. Battery life is the maker’s own test figure.
| Load | FiiO KA17 | FiiO KA5 |
|---|---|---|
| 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; FiiO KA5 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 FiiO KA5 but not on the FiiO KA17 — Symphonium Crimson.
15 headphones are left alone by the FiiO KA5 under the one-eighth rule but coloured by the FiiO KA17 (64 Audio Nio, 64 Audio Volur, Campfire Audio Andromeda 2023, 12 more).
4 headphones stay below the audible-hiss threshold on the FiiO KA5 but cross it on the FiiO KA17 (64 Audio Fourte, Campfire Audio Clara, Shure SE846, 1 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: FiiO KA17 has +5 dB of headroom there against +3 dB. 2 dB is about 1.5 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 | FiiO KA5 headroom | FiiO KA17 hiss | FiiO KA5 hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +32 dB | +33 dB | 20 dB | 19 dB |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +12 dB | +13 dB | 0 dB | -1 dB |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +19 dB | +18 dB | -1 dB | -3 dB |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +16 dB | +14 dB | -6 dB | -8 dB |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +12 dB | +12 dB | -7 dB | -9 dB |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +9 dB | +7 dB | -13 dB | -15 dB |
| Sennheiser HD 600 | 300 Ω | 6.6 mW | +5 dB | +3 dB | -17 dB | -19 dB |
| HiFiMAN Susvara | 60 Ω | 50 mW | +2 dB | +1 dB | -19 dB | -21 dB |
The FiiO KA17 costs $50 more than the FiiO KA5, 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 FiiO KA5 does not — not on power, not on the one-eighth rule, not on hiss. The traffic runs the other way: the cheaper FiiO KA5 drives one model to 100 dB, leaves 15 alone under the one-eighth rule and keeps 4 below the audible-hiss threshold that the FiiO KA17 does not.
Only published figures count here; blank axes are counted separately.