FiiO M33 R2R vs iBasso DX260 MK2

Short answer

More power: the FiiO M33 R2R, with 470 mW into 32 Ω; the iBasso DX260 MK2 has 262 mW (balanced: 1.10 W against 1.01 W). Both drive 566 of the 567 non-electrostatic headphones here to 100 dB, so on that test the difference changes nothing.
Quieter with sensitive IEMs: the iBasso DX260 MK2. 75 headphones stay below audible hiss on it but not on the FiiO M33 R2R (64 Audio Fourte, 64 Audio Nio, 64 Audio U12t, 72 more).
Output impedance: 11 headphones are left alone by the iBasso DX260 MK2 under the one-eighth rule but coloured by the FiiO M33 R2R (64 Audio Nio, 64 Audio Volur, Campfire Audio Andromeda 2023, 8 more).
Price: the iBasso DX260 MK2 costs $219 more; what that buys on these numbers is set out further down, under What the price difference buys.

Both are portable players, $730 against $949.

On raw power they are level: each reaches 100 dB on 566 of the 567 non-electrostatic models here.

Specification	FiiO M33 R2R	iBasso DX260 MK2
Power into 32Ω	470 mW	262 mW
Power into 150Ω	109 mW	56 mW
Power into 300Ω	60 mW	28 mW
Power into 600Ω	30 mW	14 mW
Output impedance	0.8 Ω	0.6 Ω
Output noise	5.5 µV	1.0 µV
Price	$730	$949
Headphones it reaches 100 dB on out of 567	566	566

Specification

FiiO M33 R2R

iBasso DX260 MK2

Power into 32Ω

470 mW

262 mW

Power into 150Ω

109 mW

56 mW

Power into 300Ω

60 mW

28 mW

Power into 600Ω

30 mW

14 mW

Output impedance

0.8 Ω

0.6 Ω

Output noise

5.5 µV

1.0 µV

Price

$730

$949

Headphones it reaches 100 dB on
out of 567

566

The 4.4 mm or XLR socket, rated on its own

Balanced	FiiO M33 R2R	iBasso DX260 MK2
Socket	4.4mm	4.4mm
Power into 32Ω	1.1 W	1.0 W
Power into 300Ω	240 mW	108 mW derived
Output impedance	1.5 Ω	1.1 Ω
Output noise	10.3 µV	1.0 µV
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.

Where each power figure comes from

Load	FiiO M33 R2R	iBasso DX260 MK2
32 Ω	Published	Derived
150 Ω	Derived	Derived
300 Ω	Published	Derived
600 Ω	Derived	Derived

Only one of these two columns starts from a power rating. FiiO M33 R2R publishes one at 32 Ω and at 300 Ω; iBasso DX260 MK2 publishes none at any of these four loads, so its column is worked out from power it published at other loads. Both are arithmetic on a maker’s own figures rather than guesses, and the method used for the iBasso DX260 MK2 understates rather than flatters — but at 32 Ω and at 300 Ω are the only loads here at which its maker can be held to a figure.

What the labels mean.

The headphones that tell them apart

On power they are interchangeable across this whole database: there is no headphone here that one reaches 100 dB on and the other does not.

11 headphones are left alone by the iBasso DX260 MK2 under the one-eighth rule but coloured by the FiiO M33 R2R (64 Audio Nio, 64 Audio Volur, Campfire Audio Andromeda 2023, 8 more).

75 headphones stay below the audible-hiss threshold on the iBasso DX260 MK2 but cross it on the FiiO M33 R2R (64 Audio Fourte, 64 Audio Nio, 64 Audio U12t, 72 more).

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

Headroom and hiss on 8 models, both sources

Headroom is at a 100 dB SPL peak.

The widest gap on the list is the Sennheiser HD 600: FiiO M33 R2R has +10 dB of headroom there against +6 dB. 3 dB is about 2.1 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 M33 R2R headroom	iBasso DX260 MK2 headroom	FiiO M33 R2R hiss	iBasso DX260 MK2 hiss
Shure SE846	9 Ω	0.04 mW	+39 dB	+39 dB	29 dB	14 dB
Campfire Audio Andromeda 2020	9 Ω	4.0 mW	+19 dB	+19 dB	9 dB	-6 dB
Audeze LCD-2 Classic	70 Ω	0.79 mW	+24 dB	+22 dB	7 dB	-7 dB
Beyerdynamic DT 1990 Pro (250Ω)	250 Ω	0.63 mW	+20 dB	+17 dB	3 dB	-12 dB
HiFiMAN HE400se	25 Ω	7.9 mW	+18 dB	+16 dB	2 dB	-13 dB
Audio-Technica ATH-R70X	470 Ω	1.6 mW	+14 dB	+11 dB	-4 dB	-19 dB
Sennheiser HD 600	300 Ω	6.6 mW	+10 dB	+6 dB	-8 dB	-23 dB
HiFiMAN Susvara	60 Ω	50 mW	+7 dB	+4 dB	-10 dB	-25 dB

The gap in dollars, against the gap in numbers

The iBasso DX260 MK2 costs $219 more than the FiiO M33 R2R. Out of the 567 models here, that difference buys 11 more models left alone under the one-eighth rule and 75 more models kept below the audible-hiss threshold.

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.