Does the Apple USB-C to 3.5mm drive the Fostex T50RP Mk3?

Computed from measured specifications · target SPL 110 dB · load 32 Ω

Insufficient

The Apple Apple USB-C to 3.5mm cannot drive the Fostex T50RP Mk3 to target SPL (~-6.0 dB headroom at 32 ohms; needs ~123.0 mW, delivers 31 mW).

Headroom
-6.0 dB
Required (110 dB SPL)
123.0 mW
Delivered (@ 32 Ω)
31 mW
Required voltage
2.57 Vrms

Power Headroom

Headroom: -6.0 dB 0 · target -6.0 dB below target marginal adequate ample -14 dB +10 +20 +36 dB

Amp delivers 31 mW at 32 Ω — short of the 123.0 mW needed to reach 110 dB SPL (-6.0 dB). Scale: -14 dB to +36 dB.

Fostex T50RP Mk3 Planar · over-ear
Impedance (rated) 50 Ω
Impedance (measured) Source: reference-audio-analyzer.pro/en/r… 53.65 Ω measured
Sensitivity (rated) 91.0 dB/mW
Sensitivity (measured) 89.1 dB/mW measured
Driver Planar
Spec basis Measured
Measured by Reference Audio Analyzer (https://reference-audio-analyzer.pro/en/report/hp/fostex-t50rp-mk3.php) · Source ↗
Apple USB-C to 3.5mm Dongle · Single Ended
Output impedance review-measured 1.0 Ω
Power @ 32 Ω 31 mW
Power @ 300 Ω 3 mW *est.
Power @ 600 Ω 1 mW *est.
Power source Review Measured low confidence
* Loads marked "est." are derived from the published voltage ceiling at a lower-impedance load (V = √(P·R) → P_higher = V²/R_higher). All derivations are upward only.
Apple does not publish power specs. Power (31 mW @ 32 Ω) from community measurements (Kinemoss Tech review 2025). Output impedance ~1 Ω from multiple independent measurements. Derives 300 Ω and 600 Ω from voltage ceiling. Replaces synthetic 'Generic USB-C dongle' fixture. · Source ↗
Planar driver note

Planar-magnetic headphones can have high current demands that are not fully captured by the power headroom model. Even with adequate headroom, some solid-state amps may struggle to deliver sufficient peak current for transient dynamics. Prefer amps rated for low-impedance planars.

Specification confidence: low

One or more amp specifications (power output or output impedance) are estimated rather than published by the manufacturer. Treat this pairing's verdict as approximate.

Where to buy

Apple USB-C to 3.5mm on Amazon ↗ Fostex T50RP Mk3 on Amazon ↗

Disclosure: links above are Amazon affiliate links. As an Amazon Associate this site earns from qualifying purchases — at no extra cost to you. Affiliate commissions do not influence verdicts; all analysis is computed independently from the data.

AmplifierHeadroom
Schiit Lyr 3 Ample 16.9 dB
JDS Labs Atom Amp 2 Ample 13.3 dB
Topping DX3 Pro+ Ample 11.7 dB
Schiit Magni Heretic Ample 11.1 dB
Schiit Fulla 4 Marginal 0.9 dB
Little Dot MkII Insufficient -0.9 dB

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HeadphoneHeadroom
Koss Porta Pro Ample 10.5 dB
Grado SR80x Ample 10.2 dB
HiFiMan Arya Insufficient -0.1 dB
AKG K702 Insufficient -0.7 dB
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Beyerdynamic DT 990 Pro Insufficient -11.5 dB

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