Does the FiiO K7 drive the Fostex T50RP Mk3?

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

Adequate

The FiiO K7 adequately drives the Fostex T50RP Mk3 with limited margin (~10.0 dB headroom at 32 ohms; needs ~123.0 mW, delivers 1220 mW).

Headroom
10.0 dB
Required (110 dB SPL)
123.0 mW
Delivered (@ 32 Ω)
1220 mW
Required voltage
2.57 Vrms

Power Headroom

Headroom: 10.0 dB 0 · target 10.0 dB below target marginal adequate ample -14 dB +10 +20 +36 dB

Scale shows dB headroom above the 123.0 mW required to reach 110 dB SPL. Amp delivers 1220 mW at 32 Ω (+10.0 dB above target).

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 ↗
FiiO K7 Dac Amp · Single Ended
Output impedance manufacturer 1.0 Ω
Power @ 32 Ω 1220 mW
Power @ 300 Ω 140 mW
Power @ 600 Ω 70 mW *est.
Power source Manufacturer
* 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.
FiiO K7 SE headphone output from manufacturer spec page (fiio.com/k7_parameters): L+R ≥ 1220 mW+1220 mW @ 32 Ω, L+R ≥ 140 mW+140 mW @ 300 Ω (THD+N<1%). Output impedance <1 Ω @ 32 Ω from manufacturer. 600 Ω derived from 300 Ω. · 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.

Where to buy

FiiO K7 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
Little Dot MkII Insufficient -0.9 dB
Apple USB-C to 3.5mm Insufficient -6.0 dB

See all amplifiers for the Fostex T50RP Mk3 →

HeadphoneHeadroom
Koss Porta Pro Ample 26.5 dB
Grado SR80x Ample 26.2 dB
HiFiMan Arya Ample 15.8 dB
AKG K702 Ample 15.2 dB
Beyerdynamic DT 770 Pro 250 Adequate 5.9 dB
Beyerdynamic DT 990 Pro Adequate 4.8 dB

See all headphones for the FiiO K7 →