Apogee BOOM vs Roland BRIDGE CAST

Short answer

More power: the Apogee BOOM, with 240 mW into 32 Ω; the Roland BRIDGE CAST has 78 mW. The Apogee BOOM drives 7 headphones to 100 dB that the Roland BRIDGE CAST cannot (Moondrop COSMO, Moondrop PARA 2, Moondrop VENUS, 4 more).
Hiss with sensitive IEMs: cannot be compared — neither maker publishes a noise figure.
Output impedance: 509 headphones are left alone by the Apogee BOOM under the one-eighth rule but coloured by the Roland BRIDGE CAST (64 Audio Aspire 1, 64 Audio Fourte, 64 Audio Nio, 506 more).
Price: the Apogee BOOM costs $41 less, and wherever both makers publish a figure the Roland BRIDGE CAST shows no advantage for the extra money.

Both are audio interfaces, $299 against $340.

The Apogee BOOM reaches 100 dB on 565 of the 567 models here, the Roland BRIDGE CAST on 558.

Every published figure, next to each other

Specification	Apogee BOOM	Roland BRIDGE CAST
Power into 32Ω	240 mW	78 mW
Power into 150Ω	51 mW	36 mW
Power into 300Ω	26 mW	29 mW
Power into 600Ω	13 mW	15 mW
Output impedance	0.5 Ω	10 Ω
Output noise	not published	not published
Price	$299	$340
Headphones it reaches 100 dB on out of 567	565	558

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

Where each power figure comes from

Load	Apogee BOOM	Roland BRIDGE CAST
32 Ω	Published	Published
150 Ω	Derived	Derived
300 Ω	Derived	Derived
600 Ω	Derived	Derived

Both makers publish a power rating. Apogee BOOM publishes at 32 Ω; Roland BRIDGE CAST at 32 Ω. The other rows are worked out from those.

The two publish at the same loads, which is the one case where the rows of this table can be read straight across.

What the labels mean.

The headphones that tell them apart

7 headphones reach 100 dB on the Apogee BOOM but not on the Roland BRIDGE CAST — Moondrop COSMO, Moondrop PARA 2, Moondrop VENUS, 4 more.

509 headphones are left alone by the Apogee BOOM under the one-eighth rule but coloured by the Roland BRIDGE CAST (64 Audio Aspire 1, 64 Audio Fourte, 64 Audio Nio, 506 more).

558 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 HiFiMAN HE400se: Apogee BOOM has +14 dB of headroom there against +9 dB. 5 dB is about 3.1 times the power, which matters for peaks rather than for how loud the music sits.

The hiss columns are empty for Apogee BOOM and Roland BRIDGE CAST because neither maker publishes no output noise figure.

Headphone	Impedance	Needs	Apogee BOOM headroom	Roland BRIDGE CAST headroom	Apogee BOOM hiss	Roland BRIDGE CAST hiss
Shure SE846	9 Ω	0.04 mW	+32 dB	+27 dB damping	not published	not published
Campfire Audio Andromeda 2020	9 Ω	4.0 mW	+12 dB	+7 dB damping	not published	not published
Audeze LCD-2 Classic	70 Ω	0.79 mW	+21 dB	+18 dB damping	not published	not published
Beyerdynamic DT 1990 Pro (250Ω)	250 Ω	0.63 mW	+17 dB	+17 dB	not published	not published
HiFiMAN HE400se	25 Ω	7.9 mW	+14 dB	+9 dB damping	not published	not published
Audio-Technica ATH-R70X	470 Ω	1.6 mW	+10 dB	+11 dB	not published	not published
Sennheiser HD 600	300 Ω	6.6 mW	+6 dB	+6 dB	not published	not published
HiFiMAN Susvara	60 Ω	50 mW	+4 dB	+0 dB damping	not published	not published

The gap in dollars, against the gap in numbers

The Roland BRIDGE CAST costs $41 more than the Apogee BOOM, and on these three axes the money buys nothing: among the 567 models here there is not one that the Roland BRIDGE CAST handles and the Apogee BOOM does not — not on power, not on the one-eighth rule, not on hiss. The traffic runs the other way: the cheaper Apogee BOOM drives 7 models to 100 dB and leaves 509 alone under the one-eighth rule that the Roland BRIDGE CAST does not.

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