Roland BRIDGE CAST: power output and what it will drive

The Roland BRIDGE CAST is an audio interface at $340. It delivers 78 mW into 32Ω and 29 mW into 300Ω, which ranks it 232 of 280 for raw power among the sources in this database.

Measured at 100 dB SPL it has comfortable headroom on 490 of the 567 dynamic and planar headphones catalogued here, enough but not generous on 63, only marginal on 5 and not enough power for 9. Power is published at 32Ω, 250Ω; the rest of the table is derived from those figures. Output noise is not published, so the hiss estimate cannot be run.

The manufacturer publishes 78 mW into 32Ω, 35 mW into 250Ω. Everything else in the table above is worked out from those figures, and this table says which is which.

Derivation holds output voltage steady between and beyond the published loads rather than output power, because that is what an amplifier actually does. The full method is written up here.

Source: roland.com.

Ordered from easiest to hardest to drive. Headroom is measured at 100 dB SPL, which is louder than almost anyone listens — a small negative number means the source still plays loud, just without reserve for peaks.

These figures come from each manufacturer's own sensitivity rating. A handful of planars — the HiFiMAN Susvara and the Abyss AB-1266 in particular — are widely reported to need far more than their published sensitivity implies, so treat a bare pass on those as optimistic rather than settled.

The manufacturer does not publish an output noise figure for this source, so the hiss estimate that runs on every other page here cannot be run on this one. Rather than substitute a plausible number, this page leaves the question open.

If you know the noise figure from a measurement you trust, the hiss calculator takes it directly and tells you where that noise lands in your own in-ears.

At 10Ω output impedance, the one-eighth rule says this source suits headphones of 80.0Ω and above. 510 of the 567 models here fall below that. That is most of the database, not a niche — 222 of them multi-driver in-ears, and the mismatch tilts the frequency response audibly rather than subtly.

The rule is a rule of thumb, not physics: a source impedance below one eighth of the headphone's keeps the interaction under about 1 dB. The checker works it out for any pair.

Of the 280 sources here, 46 do everything the Roland BRIDGE CAST does as a headphone output: reach 100 dB on every headphone it reaches and stay inside the one-eighth rule wherever it does. The cheapest of them is the FiiO KA11 at $29, against this one’s $340 — $311 less, and a USB dongle rather than an audio interface.

The cheaper one also publishes a noise figure, which the Roland BRIDGE CAST does not — so on the paperwork it is ahead, not merely level.

This counts a headphone output and nothing else. Inputs, converters, microphone preamps, balanced outputs, the volume control, the case and the warranty are all outside it, and any of them can be the reason to buy the dearer box. What the count does say is that the three numbers a maker can be held to do not separate them.

Worked out in advance against its closest rivals: vs Apogee BOOM · vs Audient iD14 MkII · vs IK Multimedia AXE I/O · vs M-Audio AIR 192|14 · vs Roland Rubix22 · vs Roland Rubix44. Each of those pages lists the headphones that tell the two apart.

Or put any two side by side in the source comparison tool, or run your own headphones through the amplifier matcher. Or see every Roland source in the database, and how much of what this site says about them came from Roland’s own documents.