Does the Schiit Fulla 4 drive the Sennheiser HD 660S?

Computed from measured specifications · target SPL 110 dB · load 300 Ω

Adequate

The Schiit Fulla 4 adequately drives the Sennheiser HD 660S with limited margin (~9.5 dB headroom at 300 ohms; needs ~4.5 mW, delivers 40 mW).

Headroom
9.5 dB
Required (110 dB SPL)
4.5 mW
Delivered (@ 300 Ω)
40 mW
Required voltage
0.99 Vrms

Power Headroom

Headroom: 9.5 dB 0 · target 9.5 dB below target marginal adequate ample -14 dB +10 +20 +36 dB

Scale shows dB headroom above the 4.5 mW required to reach 110 dB SPL. Amp delivers 40 mW at 300 Ω (+9.5 dB above target).

Sennheiser HD 660S Dynamic · over-ear
Impedance (rated) 150 Ω
Impedance (measured) Source: reference-audio-analyzer.pro/en/r… 216.75 Ω measured
Sensitivity (rated) 104.0 dB/mW
Sensitivity (measured) 103.45 dB/mW measured
Driver Dynamic
Spec basis Measured
Measured by Reference Audio Analyzer (https://reference-audio-analyzer.pro/en/report/hp/sennheiser-hd-660s.php) · Source ↗
Schiit Fulla 4 Dac Amp · Single Ended
Output impedance manufacturer 0.5 Ω
Power @ 16 Ω 300 mW
Power @ 32 Ω 200 mW
Power @ 50 Ω 150 mW
Power @ 300 Ω 40 mW
Power @ 600 Ω 20 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.
Schiit Fulla 4 manufacturer spec: 300/200/150/40 mW at 16/32/50/300 Ω. NOTE: prior project fixture used 400/300/220/40 — those figures match the Fulla 3 or an earlier revision; updated to Fulla 4 (current product). Output impedance from Schiit spec. · Source ↗

Where to buy

Schiit Fulla 4 on Amazon ↗ Sennheiser HD 660S 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 23.0 dB
Schiit Valhalla 2 Ample 22.5 dB
Little Dot MkII Ample 18.2 dB
Topping L30 Ample 17.9 dB
iFi Zen DAC V2 Adequate 9.0 dB
Apple USB-C to 3.5mm Insufficient -1.4 dB

See all amplifiers for the Sennheiser HD 660S →

HeadphoneHeadroom
Grado SR80x Ample 18.3 dB
AKG K371 Ample 17.8 dB
HiFiMan Arya Adequate 8.0 dB
Sennheiser HD 800 S Adequate 7.6 dB
Beyerdynamic DT 770 Pro 250 Marginal 0.5 dB
Beyerdynamic DT 990 Pro Insufficient -0.6 dB

See all headphones for the Schiit Fulla 4 →