Does the Darkvoice 336SE drive the Sennheiser HD 660S?

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

Ample OTL-compatible pairing

The Darkvoice Darkvoice 336SE drives the Sennheiser HD 660S with ample headroom (~17.4 dB headroom at 300 ohms; needs ~4.5 mW, delivers 250 mW). This OTL tube amp suits the headphone's impedance (217 Ω) — a classically compatible pairing for high-output-impedance tube sources.

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

Power Headroom

Headroom: 17.4 dB 0 · target 17.4 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 250 mW at 300 Ω (+17.4 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 ↗
Darkvoice 336SE Desktop Tube · Single Ended
Output impedance assumed 100.0 Ω estimated
Power @ 300 Ω 250 mW
Power @ 600 Ω 125 mW *est.
Power source Estimated 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.
OTL tube amp using 6N5P output tubes. Manufacturer page (Apos, analogmetric) states only 'Power handling capacity: 1 W' with no load specification. Power figure of 250 mW @ 300 Ω is a conservative estimate based on OTL topology similar to the Bottlehead Crack; treat as approximate. Output impedance of 100 Ω is estimated from OTL/6N5P tube topology — manufacturer does not publish this figure. 600 Ω derived from 300 Ω. · Source ↗
Impedance compatibility

This OTL tube amp's high output impedance (100 Ω) is a good match for the Sennheiser HD 660S's 216 Ω impedance. The impedance ratio (2.2×) falls within the recommended range for high-output-impedance tube sources — a classically well-matched pairing.

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

Darkvoice 336SE 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.

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