Overview

The Superlux HD681F are semi-open, circumaural studio headphones with 50 mm neodymium drivers and a “front row” tuning aimed at flat, vocal-forward reproduction within the HD681 family [1]. Official specs list 32 Ω impedance, 98 dB SPL (1 mW) sensitivity, and a 10–30,000 Hz frequency range; a 2.5 m single-sided cable and 3.5→6.3 mm adapter are included [1][2].

Scientific Validity

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Independent, model-specific measurements for HD681F remain limited. Per manufacturer specs: 32 Ω, 98 dB SPL (1 mW), max input 300 mW, and 10–30 kHz bandwidth [1][2]. Within the HD681 family, third-party data on the HD681 (non-F) shows good mid-range target compliance (RMS deviation ≈ 1.01 dB), fair treble compliance, and weighted harmonic distortion ≈ 0.145 % @ 90 dB and 0.313 % @ 100 dB—below problematic thresholds for headphones [3]. Because these data are not for the F variant, we provisionally center the score at 0.5 and will adjust when HD681F-specific FR/THD measurements (±dB curves, test conditions) are published.

Technology Level

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The design uses well-established elements: 50 mm dynamic drivers with neodymium magnets, self-adjusting headband, and a simple semi-open venting scheme [1][2]. No proprietary transducer tech, materials, or novel acoustical architecture is claimed; execution is competent but conventional.

Cost-Performance

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Current market price: 28 USD (Thomann US) [2]. We surveyed cheaper or similarly priced semi-open “monitoring” models:

• Superlux HD681 (non-F) at 24.30 USD: similar form factor but measured tuning is brighter (mid-treble emphasis) rather than flat/vocal-forward; not judged equivalent for “flat” monitoring intent [2][3].
• Samson SR850 commonly ≈ 33 USD in 2025 (Amazon price history) with bright treble per independent measurements [4][6].

Given the lack of a cheaper product with equivalent-or-better user-visible functions and measured/claimed flatness, we set CP = 1.0 and explicitly note no cheaper equivalent identified at review time. If a cheaper equal-or-better option appears, CP will be revised accordingly.

Reliability & Support

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Build is lightweight plastic with leatherette pads; long-term durability is modest but typical for the price bracket [2][3]. Family-level measurements (HD681 non-F) indicate sample variance—e.g., sub-bass ±5 dB and larger variance >10 kHz across units—which cautions expectations; HD681F variance isn’t separately documented [5]. Warranty terms depend on the retailer; for example, Thomann lists a 30-day return and 3-year retailer warranty program [7]. Overall support outlook is average.

Rationality of Design Philosophy

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Targeting a neutral/“front row” response at a very low price is a rational, measurement-oriented goal for vocal-centric monitoring [1]. The feature set avoids costly, non-audible “audio-myth” embellishments and focuses on fundamentals (fit, simple semi-open acoustics). Absent HD681F-specific third-party data, we withhold a higher score.

Advice

The HD681F is a strong entry point for budget monitoring where vocal clarity and broadly flat balance are desired—tracking, editing, and mix checks in quiet rooms. Expect limited isolation and some sound leakage due to the semi-open design [2][3]. If you need more bass presence or a different balance, consider equalization; if you need isolation, choose a closed-back alternative. Purchase from retailers with clear returns to mitigate potential unit-to-unit variance [5][7].

References

[1] Superlux, “HD681 Series — Information Sheet” (brochure; specs and tuning descriptions). https://images.thomann.de/pics/atg/atgdata/document/specs/218865_240434_240433_en_online.pdf (accessed 2025-08-20).
[2] Thomann, “Superlux HD-681 F — Product Page” (price, specs, included items). https://www.thomannmusic.com/superlux_hd681_f.htm (accessed 2025-08-20).
[3] RTINGS, “Superlux HD 681 – Review & Measurements” (FR compliance, WHD values). https://www.rtings.com/headphones/reviews/superlux/hd-681 (accessed 2025-08-20).
[4] RTINGS, “Samson SR850 – Review & Measurements” (bright treble; measurement context). https://www.rtings.com/headphones/reviews/samson/sr850 (accessed 2025-08-20).
[5] Sonarworks, “Superlux HD 681 Studio Headphone Review” (unit variance ± 5 dB sub-bass; consistency notes). https://www.sonarworks.com/blog/reviews/superlux-hd-681-studio-headphone-review (accessed 2025-08-20).
[6] CamelCamelCamel, “Samson SR850 Price History (Amazon US)” (typical new price ≈ 33 USD mid-2025). https://camelcamelcamel.com/product/B002LBSEQS (accessed 2025-08-20).
[7] Thomann, “Buy Headphones at Thomann – Benefits” (30-day return, 3-year warranty). https://www.thomannmusic.com/headphones.html (accessed 2025-08-20).

(2025.8.20)