Short answer
Both are dongles, both at $79.
The FiiO KA3 reaches 100 dB on 565 of the 567 models here, the FiiO KA13 on 555.
| Specification | FiiO KA13 | FiiO KA3 |
|---|---|---|
| Power into 32Ω | 50 mW | 130 mW |
| Power into 150Ω | 10 mW | 28 mW |
| Power into 300Ω | 5.0 mW | 14 mW |
| Power into 600Ω | 2.5 mW | 7.0 mW |
| Output impedance | 1.7 Ω | 0.5 Ω |
| Output noise | 2.5 µV | 1.7 µV |
| Price | $79 | $79 |
| Headphones it reaches 100 dB on out of 567 | 555 | 565 |
| Balanced | FiiO KA13 | FiiO KA3 |
|---|---|---|
| Socket | 4.4mm | 4.4mm |
| Power into 32Ω | 260 mW | 240 mW |
| Power into 300Ω | 20 mW | 56 mW |
| Output impedance | 1.8 Ω | 0.7 Ω |
| Output noise | 4.6 µV | 2.9 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 KA13 | FiiO KA3 |
|---|---|---|
| DAC | CS43131 x2 | ES9038Q2M (amp: RT6863D x2) |
| Outputs | 3.5 mm SE (shared with S/PDIF coaxial out), 4.4 mm balanced | 3.5 mm, 4.4 mm balanced |
| Connection | USB-C | USB-C |
| Formats | PCM 384 kHz/32-bit, DSD64/128/256; coaxial 384 kHz/32-bit | PCM 768 kHz/32-bit, DSD64/128/256/512 |
| Weight | 19 g | 17.5 g |
| Dimensions | About 56.5 x 22 x 10.5 mm | 56.3 x 20.2 x 12 mm |
Copied from the makers’ own pages: fiio.com/ka13_parameters, fiio.com/ka3_parameters. Battery life is the maker’s own test figure.
| Load | FiiO KA13 | FiiO KA3 |
|---|---|---|
| 32 Ω | Published | Published |
| 150 Ω | Derived | Derived |
| 300 Ω | Published | Published |
| 600 Ω | Derived | Published |
Both makers publish a power rating. FiiO KA13 publishes at 32 Ω and at 300 Ω; FiiO KA3 at 32 Ω, at 300 Ω and at 600 Ω. The other rows are worked out from those.
So the two columns are not equally firm row by row: at 600 Ω only the FiiO KA3 figure is the maker’s own. On those rows the derived number is the one to doubt first.
10 headphones reach 100 dB on the FiiO KA3 but not on the FiiO KA13 — Beyerdynamic DT 880 Edition (600Ω), Beyerdynamic DT 990 Edition (600Ω), HiFiMAN HE-6se V2, 7 more.
66 headphones are left alone by the FiiO KA3 under the one-eighth rule but coloured by the FiiO KA13 (64 Audio Aspire 1, 64 Audio Fourte, 64 Audio Nio, 63 more).
8 headphones stay below the audible-hiss threshold on the FiiO KA3 but cross it on the FiiO KA13 (64 Audio Fourte, Campfire Audio Andromeda 10, Campfire Audio Andromeda 2023, 5 more).
555 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 KA3 has +3 dB of headroom there against -1 dB. 4 dB is about 2.8 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 KA13 headroom | FiiO KA3 headroom | FiiO KA13 hiss | FiiO KA3 hiss |
|---|---|---|---|---|---|---|
| Shure SE846 | 9 Ω | 0.04 mW | +30 dB damping | +32 dB | 22 dB | 19 dB |
| Campfire Audio Andromeda 2020 | 9 Ω | 4.0 mW | +10 dB damping | +12 dB | 2 dB | -1 dB |
| Audeze LCD-2 Classic | 70 Ω | 0.79 mW | +15 dB | +19 dB | 1 dB | -3 dB |
| Beyerdynamic DT 1990 Pro (250Ω) | 250 Ω | 0.63 mW | +10 dB | +14 dB | -4 dB | -7 dB |
| HiFiMAN HE400se | 25 Ω | 7.9 mW | +8 dB | +12 dB | -5 dB | -8 dB |
| Audio-Technica ATH-R70X | 470 Ω | 1.6 mW | +3 dB | +8 dB | -11 dB | -14 dB |
| Sennheiser HD 600 | 300 Ω | 6.6 mW | -1 dB | +3 dB | -15 dB | -18 dB |
| HiFiMAN Susvara | 60 Ω | 50 mW | -3 dB | +1 dB | -17 dB | -20 dB |
These two cost the same, $79, so price settles nothing. Out of the 567 models here, the FiiO KA3 drives 10 models to 100 dB, leaves 66 alone under the one-eighth rule and keeps 8 below the audible-hiss threshold — and on the other side there is no such advantage at all.
Only published figures count here; blank axes are counted separately.