Audient iD48 vs RME ADI-2 DAC FS

Short answer

More power: the RME ADI-2 DAC FS, with 1.20 W into 32 Ω; the Audient iD48 has 528 mW. The RME ADI-2 DAC FS drives 1 headphone to 100 dB that the Audient iD48 cannot (Symphonium Titan).
Hiss with sensitive IEMs: cannot be compared — the maker of the Audient iD48 publishes no noise figure.
Output impedance: 561 headphones are left alone by the RME ADI-2 DAC FS under the one-eighth rule but coloured by the Audient iD48 (64 Audio Aspire 1, 64 Audio Fourte, 64 Audio Nio, 558 more).
Price: the RME ADI-2 DAC FS costs $99 more; what that buys on these numbers is set out further down, under What the price difference buys.

Both are audio interfaces, $1300 against $1399.

The RME ADI-2 DAC FS reaches 100 dB on 567 of the 567 models here, the Audient iD48 on 566.

Every published figure, next to each other

Specification	Audient iD48	RME ADI-2 DAC FS
Power into 32Ω	528 mW	1.2 W
Power into 150Ω	265 mW	256 mW
Power into 300Ω	168 mW	128 mW
Power into 600Ω	126 mW	64 mW
Output impedance	50 Ω	0.1 Ω
Output noise	not published	2.18 µV
Price	$1300	$1399
Headphones it reaches 100 dB on out of 567	566	567

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

Where each power figure comes from

Load	Audient iD48	RME ADI-2 DAC FS
32 Ω	Derived	Published
150 Ω	Derived	Derived
300 Ω	Derived	Derived
600 Ω	Published	Derived

Both makers publish a power rating. Audient iD48 publishes at 600 Ω; RME ADI-2 DAC FS at 32 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 Audient iD48 figure is the maker’s own and at 32 Ω only the RME ADI-2 DAC FS figure is the maker’s own. On those rows the derived number is the one to doubt first.

What the labels mean.

The headphones that tell them apart

1 headphone reaches 100 dB on the RME ADI-2 DAC FS but not on the Audient iD48 — Symphonium Titan.

561 headphones are left alone by the RME ADI-2 DAC FS under the one-eighth rule but coloured by the Audient iD48 (64 Audio Aspire 1, 64 Audio Fourte, 64 Audio Nio, 558 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 Shure SE846: RME ADI-2 DAC FS has +41 dB of headroom there against +36 dB. 5 dB is about 3.3 times the power, which matters for peaks rather than for how loud the music sits.

The hiss columns are empty for Audient iD48 because that maker publishes no output noise figure.

Headphone	Impedance	Needs	Audient iD48 headroom	RME ADI-2 DAC FS headroom	Audient iD48 hiss	RME ADI-2 DAC FS hiss
Shure SE846	9 Ω	0.04 mW	+36 dB damping	+41 dB	not published	21 dB
Campfire Audio Andromeda 2020	9 Ω	4.0 mW	+16 dB damping	+21 dB	not published	1 dB
Audeze LCD-2 Classic	70 Ω	0.79 mW	+28 dB damping	+28 dB	not published	-1 dB
Beyerdynamic DT 1990 Pro (250Ω)	250 Ω	0.63 mW	+25 dB damping	+24 dB	not published	-5 dB
HiFiMAN HE400se	25 Ω	7.9 mW	+17 dB damping	+21 dB	not published	-6 dB
Audio-Technica ATH-R70X	470 Ω	1.6 mW	+19 dB	+17 dB	not published	-12 dB
Sennheiser HD 600	300 Ω	6.6 mW	+14 dB damping	+13 dB	not published	-16 dB
HiFiMAN Susvara	60 Ω	50 mW	+11 dB damping	+11 dB	not published	-18 dB

The gap in dollars, against the gap in numbers

The RME ADI-2 DAC FS costs $99 more than the Audient iD48. Out of the 567 models here, that difference buys 1 more model driven to 100 dB and 561 more models left alone under the one-eighth rule.

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.