FiiO KA15 vs Onix Alpha XI1

Short answer

Power: about the same. The FiiO KA15 has 180 mW into 32 Ω, the Onix Alpha XI1 180 mW (balanced: 560 mW and 500 mW). The FiiO KA15 drives 2 headphones to 100 dB that the Onix Alpha XI1 cannot (Moondrop PARA, Symphonium Crimson).
Hiss with sensitive IEMs: cannot be compared — the maker of the Onix Alpha XI1 publishes no noise figure.
Output impedance: 11 headphones are left alone by the Onix Alpha XI1 under the one-eighth rule but coloured by the FiiO KA15 (64 Audio Nio, 64 Audio Volur, Campfire Audio Andromeda 2023, 8 more).
Price: the same, $109.

Both are dongles, both at $109.

The FiiO KA15 reaches 100 dB on 566 of the 567 models here, the Onix Alpha XI1 on 564.

Side by side

Every published figure, next to each other

Specification	FiiO KA15	Onix Alpha XI1
Power into 32Ω	180 mW	180 mW
Power into 150Ω	38 mW	38 mW
Power into 300Ω	19 mW	19 mW
Power into 600Ω	9.5 mW	9.6 mW
Output impedance	0.8 Ω	0.4 Ω
Output noise	1.7 µV	not published
Price	$109	$109
Headphones it reaches 100 dB on out of 567	566	564

Not published means the maker leaves it out, so that axis cannot be compared.

Balanced output

The 4.4 mm or XLR socket, rated on its own

Balanced	FiiO KA15	Onix Alpha XI1
Socket	4.4mm	4.4mm
Power into 32Ω	560 mW	500 mW
Power into 300Ω	78 mW	53 mW derived
Output impedance	1.2 Ω	0.8 Ω
Output noise	3.2 µV	not published
Headphones it reaches 100 dB on out of 567	566	566

Through the balanced sockets the two are level on the same test: each reaches 100 dB on 566 of the 567 models here. Derived figures are worked out from the loads the maker did publish.

How solid these numbers are

Where each power figure comes from

Load	FiiO KA15	Onix Alpha XI1
32 Ω	Published	Published
150 Ω	Derived	Derived
300 Ω	Published	Derived
600 Ω	Derived	Derived

Both makers publish a power rating. FiiO KA15 publishes at 32 Ω and at 300 Ω; Onix Alpha XI1 at 32 Ω. The other rows are worked out from those.

So the two columns are not equally firm row by row: at 300 Ω only the FiiO KA15 figure is the maker’s own. On those rows the derived number is the one to doubt first.

What the labels mean.

What separates them

The headphones that tell them apart

2 headphones reach 100 dB on the FiiO KA15 but not on the Onix Alpha XI1 — Moondrop PARA, Symphonium Crimson.

11 headphones are left alone by the Onix Alpha XI1 under the one-eighth rule but coloured by the FiiO KA15 (64 Audio Nio, 64 Audio Volur, Campfire Audio Andromeda 2023, 8 more).

564 of the 567 models here reach 100 dB on both.

On real headphones

Headroom and hiss on 8 models, both sources

Headroom is at a 100 dB SPL peak.

The widest gap on the list is the Shure SE846: FiiO KA15 has +36 dB of headroom there against +31 dB. 5 dB is about 3.2 times the power, which matters for peaks rather than for how loud the music sits.

The hiss columns are empty for Onix Alpha XI1 because that maker publishes no output noise figure.

Headphone	Impedance	Needs	FiiO KA15 headroom	Onix Alpha XI1 headroom	FiiO KA15 hiss	Onix Alpha XI1 hiss
Shure SE846	9 Ω	0.04 mW	+36 dB	+31 dB	19 dB	not published
Campfire Audio Andromeda 2020	9 Ω	4.0 mW	+16 dB	+11 dB	-1 dB	not published
Audeze LCD-2 Classic	70 Ω	0.79 mW	+20 dB	+20 dB	-3 dB	not published
Beyerdynamic DT 1990 Pro (250Ω)	250 Ω	0.63 mW	+16 dB	+16 dB	-7 dB	not published
HiFiMAN HE400se	25 Ω	7.9 mW	+14 dB	+12 dB	-8 dB	not published
Audio-Technica ATH-R70X	470 Ω	1.6 mW	+9 dB	+9 dB	-14 dB	not published
Sennheiser HD 600	300 Ω	6.6 mW	+5 dB	+5 dB	-18 dB	not published
HiFiMAN Susvara	60 Ω	50 mW	+3 dB	+3 dB	-20 dB	not published

What the price difference buys

The gap in dollars, against the gap in numbers

These two cost the same, $109, so price settles nothing. Out of the 567 models here, the FiiO KA15 drives 2 models to 100 dB; the Onix Alpha XI1 leaves 11 models alone under the one-eighth rule — and that is the whole of it on these three axes.

Only published figures count here; blank axes are counted separately.

Both pages in full

Each in full: FiiO KA15 and Onix Alpha XI1.

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