Does the Apple USB-C to 3.5mm drive the Koss Porta Pro?

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

Ample

The Apple Apple USB-C to 3.5mm drives the Koss Porta Pro with ample headroom (~10.5 dB headroom at 32 ohms; needs ~2.8 mW, delivers 31 mW).

Headroom
10.5 dB
Required (110 dB SPL)
2.8 mW
Delivered (@ 32 Ω)
31 mW
Required voltage
0.45 Vrms

Power Headroom

Headroom: 10.5 dB 0 · target 10.5 dB below target marginal adequate ample -14 dB +10 +20 +36 dB

Scale shows dB headroom above the 2.8 mW required to reach 110 dB SPL. Amp delivers 31 mW at 32 Ω (+10.5 dB above target).

Koss Porta Pro Dynamic · on-ear
Impedance (rated) 60 Ω
Impedance (measured) Source: reference-audio-analyzer.pro/en/r… 72.15 Ω measured
Sensitivity (rated) 101.0 dB/mW
Sensitivity (measured) 105.6 dB/mW measured
Driver Dynamic
Spec basis Measured
Measured by Reference Audio Analyzer (https://reference-audio-analyzer.pro/en/report/hp/koss-porta-pro.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 ↗
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 ↗ Koss Porta Pro 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 33.4 dB
JDS Labs Atom Amp 2 Ample 29.8 dB
Topping DX3 Pro+ Ample 28.2 dB
Schiit Magni Heretic Ample 27.6 dB
Schiit Fulla 4 Ample 17.4 dB
Little Dot MkII Ample 15.6 dB

See all amplifiers for the Koss Porta Pro →

HeadphoneHeadroom
Grado SR80x Ample 10.2 dB
AKG K371 Adequate 9.7 dB
AKG K702 Insufficient -0.7 dB
Sennheiser HD 660S Insufficient -1.4 dB
Beyerdynamic DT 770 Pro 250 Insufficient -10.4 dB
Beyerdynamic DT 990 Pro Insufficient -11.5 dB

See all headphones for the Apple USB-C to 3.5mm →