FiiO M17 vs iBasso DX340

Short answer

Power: about the same. The FiiO M17 has 500 mW into 32 Ω, the iBasso DX340 550 mW (balanced: 3.00 W and 2.15 W). The FiiO M17 drives 1 headphone to 100 dB that the iBasso DX340 cannot (Symphonium Titan).
Hiss with sensitive IEMs: cannot be compared — the maker of the iBasso DX340 publishes no noise figure.
Price: the FiiO M17 costs $100 more; what that buys on these numbers is set out further down, under What the price difference buys.

Both are portable players, $1799 against $1699.

The FiiO M17 reaches 100 dB on 567 of the 567 models here, the iBasso DX340 on 566.

Side by side

Every published figure, next to each other

Specification	FiiO M17	iBasso DX340
Power into 32Ω	500 mW	550 mW
Power into 150Ω	115 mW	117 mW
Power into 300Ω	63 mW	59 mW
Power into 600Ω	32 mW	29 mW
Output impedance	1 Ω	not published
Output noise	3.5 µV	not published
Price	$1799	$1699
Headphones it reaches 100 dB on out of 567	567	566

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 M17	iBasso DX340
Socket	4.4mm	4.4mm
Power into 32Ω	3.0 W	2.1 W
Power into 300Ω	250 mW	229 mW derived
Output impedance	2 Ω	not published
Output noise	7 µV	not published
Headphones it reaches 100 dB on out of 567	567	567

Through the balanced sockets the two are level on the same test: each reaches 100 dB on 567 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 M17	iBasso DX340
32 Ω	Published	Published
150 Ω	Derived	Derived
300 Ω	Published	Derived
600 Ω	Derived	Derived

Both makers publish a power rating. FiiO M17 publishes at 32 Ω and at 300 Ω; iBasso DX340 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 M17 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

1 headphone reaches 100 dB on the FiiO M17 but not on the iBasso DX340 — Symphonium Titan.

566 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 Campfire Audio Andromeda 2020: FiiO M17 has +20 dB of headroom there against +16 dB. 4 dB is about 2.7 times the power, which matters for peaks rather than for how loud the music sits.

The hiss columns are empty for iBasso DX340 because that maker publishes no output noise figure.

Headphone	Impedance	Needs	FiiO M17 headroom	iBasso DX340 headroom	FiiO M17 hiss	iBasso DX340 hiss
Shure SE846	9 Ω	0.04 mW	+40 dB	+36 dB	25 dB	not published
Campfire Audio Andromeda 2020	9 Ω	4.0 mW	+20 dB	+16 dB	5 dB	not published
Audeze LCD-2 Classic	70 Ω	0.79 mW	+25 dB	+25 dB	3 dB	not published
Beyerdynamic DT 1990 Pro (250Ω)	250 Ω	0.63 mW	+21 dB	+20 dB	-1 dB	not published
HiFiMAN HE400se	25 Ω	7.9 mW	+19 dB	+17 dB	-2 dB	not published
Audio-Technica ATH-R70X	470 Ω	1.6 mW	+14 dB	+14 dB	-8 dB	not published
Sennheiser HD 600	300 Ω	6.6 mW	+10 dB	+9 dB	-12 dB	not published
HiFiMAN Susvara	60 Ω	50 mW	+7 dB	+8 dB	-14 dB	not published

What the price difference buys

The gap in dollars, against the gap in numbers

The FiiO M17 costs $100 more than the iBasso DX340. Out of the 567 models here, that difference buys 1 more model driven to 100 dB.

Nothing runs the other way: there is no axis here on which the cheaper of the two does better.

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

Each in full: FiiO M17 and iBasso DX340.