Overview

The Benchmark HPA4 is a headphone amplifier and line preamplifier that employs the THX-888, the top-tier chip from THX Achromatic Audio Amplifier (AAA) technology. Benchmark Media Systems, founded in 1985, has built a solid track record with broadcast and recording studio equipment, with adoption records at world-class facilities such as Abbey Road Studios. The HPA4, as the company’s audiophile-focused product, pursues transparent design through measured performance excellence.

Scientific Validity

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THD+N achieves 0.00006% (-125dB) at 16Ω load. Maximum output is about 6W into 16Ω, and about 11.9 Vrms (≈0.47 W) into 300Ω [1][4]. SNR is specified at over 131 dB for headphone outputs and over 135 dB for line outputs (manufacturer specs) [4]. Frequency response is flat from 10Hz-200kHz, with -3dB points extending from 0.1Hz-500kHz [1][4]. Output impedance measures 0.6Ω at 20Hz/1kHz and 0.83Ω at 20kHz [2]. Crosstalk is below -133dB at 1kHz and -116dB at 10kHz [1]. These values significantly exceed transparent levels, providing completely transparent performance for human hearing.

Technology Level

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The THX-888 chip represents the culmination of 9 years of joint development between THX and Benchmark, implementing the highest tier of Achromatic Audio Amplifier technology [3]. The design incorporates dual-mono configuration and a precision relay-based volume control with 256 steps at 0.5dB increments [1]. However, since the core technology is a joint development with THX rather than completely in-house Benchmark technology, while representing industry-leading standards, it falls short of a perfect score.

Cost-Performance

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The HPA4’s current price is 3,499 USD [4]. As a comparison target with equivalent or superior functions and performance, the Topping A90 Discrete (599 USD) can be identified [5]. The A90D supports all functions with THD+N<0.000055%, SNR up to 145dB, achieving measured performance comparable to the HPA4 [5]. Cost-performance calculates to 599 USD ÷ 3,499 USD = 0.171.

Reliability & Support

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Benchmark Media Systems possesses over 40 years of industry experience with extensive achievements in broadcast and recording industries [3]. All products are designed, assembled, and tested at their Syracuse, New York facility, establishing a solid quality control system [3]. However, compared to emerging manufacturers, they don’t offer particularly extended warranties, resulting in an industry-standard level evaluation.

Rationality of Design Philosophy

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The clear goal of achieving transparency through measured performance and the adoption of scientifically-grounded THX AAA technology is rational [1][3]. However, this performance level already far exceeds human hearing limitations, and with equivalent performance being realized at significantly lower costs by companies like Topping, the necessity of existing as an expensive dedicated device is limited. While the direction of pursuing measured values is correct, there are concerns about rationality from a price-performance perspective.

Advice

This is an excellent choice for those seeking the highest-grade headphone amplifier with uncompromising measured performance and having sufficient budget. However, it’s important to make decisions while understanding that practically equivalent transparent performance can be obtained from alternatives like the 599 USD Topping A90 Discrete. For those who value professional equipment brand value and long-term support systems, the HPA4’s value increases. For general music listening purposes, consider that more affordable alternatives are likely to achieve auditorily indistinguishable results.

References

[1] Stereophile, “Benchmark HPA4 headphone amplifier/line preamplifier Measurements”, https://www.stereophile.com/content/benchmark-hpa4-headphone-amplifierline-preamplifier-measurements, March 2019

[2] Stereophile, “Benchmark HPA4 headphone amplifier/line preamplifier”, https://www.stereophile.com/content/benchmark-hpa4-headphone-amplifierline-preamplifier, March 2019

[3] Benchmark Media Systems, “Company Information”, https://benchmarkmedia.com/pages/company-information, 2025

[4] Benchmark Media Systems, “HPA4 Headphone / Line Amplifier”, https://benchmarkmedia.com/products/hpa4, 2025

[5] Apos Audio, “TOPPING A90 Discrete Headphone Amp”, https://apos.audio/products/topping-a90-headphone-amp, 2025

(2025.8.10)