MOTU M2 vs Tascam US-2x2HR

Short answer

More power: the MOTU M2, with 333 mW into 32 Ω; the Tascam US-2x2HR has 18 mW. The MOTU M2 drives 24 headphones to 100 dB that the Tascam US-2x2HR cannot (Abyss AB-1266 Phi TC, Audeze LCD-5, Dan Clark Audio AEON 2 Closed, 21 more).
Hiss with sensitive IEMs: cannot be compared — neither maker publishes a noise figure.
Price: the MOTU M2 costs $20 more; what that buys on these numbers is set out further down, under What the price difference buys.

Both are audio interfaces, $219 against $199.

The MOTU M2 reaches 100 dB on 565 of the 567 models here, the Tascam US-2x2HR on 541.

Side by side

Every published figure, next to each other

Specification	MOTU M2	Tascam US-2x2HR
Power into 32Ω	333 mW	18 mW
Power into 150Ω	71 mW	17 mW
Power into 300Ω	36 mW	12 mW
Power into 600Ω	18 mW	7.3 mW
Output impedance	not published	66 Ω
Output noise	not published	not published
Price	$219	$199
Headphones it reaches 100 dB on out of 567	565	541

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

How solid these numbers are

Where each power figure comes from

Load	MOTU M2	Tascam US-2x2HR
32 Ω	Upper bound	Published
150 Ω	Upper bound	Derived
300 Ω	Upper bound	Derived
600 Ω	Upper bound	Derived

These two columns are not the same kind of number, and that matters more than the gap between them. Tascam US-2x2HR publishes a power rating (at 32 Ω); MOTU M2 publishes no power figure at any load, only a maximum output voltage, so every milliwatt in its column is a ceiling worked out from that voltage.

A ceiling assumes the amplifier holds that voltage into the load, and nothing on MOTU M2’s own sheet says it does. It is the most flattering reading available, and it is used here only because the alternative is a blank. Where the MOTU M2 column looks the stronger of the two, treat the difference as unproven rather than measured. 24 of the 280 sources here are in that position, with no published power rating at any load.

What the labels mean.

What separates them

The headphones that tell them apart

24 headphones reach 100 dB on the MOTU M2 but not on the Tascam US-2x2HR — Abyss AB-1266 Phi TC, Audeze LCD-5, Dan Clark Audio AEON 2 Closed, 21 more.

541 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 HiFiMAN HE400se: MOTU M2 has +15 dB of headroom there against +2 dB. 13 dB is about 19 times the power, which matters for peaks rather than for how loud the music sits.

The hiss columns are empty for MOTU M2 and Tascam US-2x2HR because neither maker publishes no output noise figure.

Headphone	Impedance	Needs	MOTU M2 headroom	Tascam US-2x2HR headroom	MOTU M2 hiss	Tascam US-2x2HR hiss
Shure SE846	9 Ω	0.04 mW	+34 dB	+21 dB damping	not published	not published
Campfire Audio Andromeda 2020	9 Ω	4.0 mW	+14 dB	+1 dB damping	not published	not published
Audeze LCD-2 Classic	70 Ω	0.79 mW	+23 dB	+13 dB damping	not published	not published
Beyerdynamic DT 1990 Pro (250Ω)	250 Ω	0.63 mW	+18 dB	+13 dB damping	not published	not published
HiFiMAN HE400se	25 Ω	7.9 mW	+15 dB	+2 dB damping	not published	not published
Audio-Technica ATH-R70X	470 Ω	1.6 mW	+12 dB	+7 dB damping	not published	not published
Sennheiser HD 600	300 Ω	6.6 mW	+7 dB	+3 dB damping	not published	not published
HiFiMAN Susvara	60 Ω	50 mW	+5 dB	-5 dB damping	not published	not published

What the price difference buys

The gap in dollars, against the gap in numbers

The MOTU M2 costs $20 more than the Tascam US-2x2HR. Out of the 567 models here, that difference buys 24 more models 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: MOTU M2 and Tascam US-2x2HR.