Benchmark HPA4 Silver - front view
Benchmark HPA4 Silver Rack Mount
Benchmark HPA4 Black Rackmount
Benchmark HPA4 - rear view
Benchmark Remote Control
Benchmark HPA4 Silver - front view
Benchmark HPA4 Silver - front right
Benchmark HPA4 Silver - angle left
Capacitive Touch Screen - includes large text feature
Benchmark HPA4 Silver - top front
Benchmark HPA4 Black with Remote Control
Benchmark HPA4 Black - front view
Benchmark HPA4 Black - left front
Benchmark HPA4 Black - left side
Benchmark HPA4 Black Rackmount - left front
Everything Audio Network 2018 Product of the Year
AV Tech Media Awards - Best Headphone Amplifier
Everything Audio Network - Stellar Sound Award
Hi-Fi News - Outstanding Product Award
The Absolute Sound - 2021 Editors' Choice Award
Home Theater and High Fidelity - Best High-End Stereo Preamplifier 2021
Home Theater and High Fidelity - Best of 2021 Award
Secrets - Reference Component Award
Benchmark HPA4 Silver - front view
Benchmark HPA4 Silver Rack Mount
Benchmark HPA4 Black Rackmount
Benchmark HPA4 - rear view
Benchmark Remote Control
Benchmark HPA4 Silver - front view
Benchmark HPA4 Silver - front right
Benchmark HPA4 Silver - angle left
Capacitive Touch Screen - includes large text feature
Benchmark HPA4 Silver - top front
Benchmark HPA4 Black with Remote Control
Benchmark HPA4 Black - front view
Benchmark HPA4 Black - left front
Benchmark HPA4 Black - left side
Benchmark HPA4 Black Rackmount - left front
Everything Audio Network 2018 Product of the Year
AV Tech Media Awards - Best Headphone Amplifier
Everything Audio Network - Stellar Sound Award
Hi-Fi News - Outstanding Product Award
The Absolute Sound - 2021 Editors' Choice Award
Home Theater and High Fidelity - Best High-End Stereo Preamplifier 2021
Home Theater and High Fidelity - Best of 2021 Award
Secrets - Reference Component Award
Benchmark HPA4 Silver - front view
Benchmark HPA4 Silver Rack Mount
Benchmark HPA4 Black Rackmount
Benchmark HPA4 - rear view
Benchmark Remote Control
Benchmark HPA4 Silver - front view
Benchmark HPA4 Silver - front right
Benchmark HPA4 Silver - angle left
Capacitive Touch Screen - includes large text feature
Benchmark HPA4 Silver - top front
Benchmark HPA4 Black with Remote Control
Benchmark HPA4 Black - front view
Benchmark HPA4 Black - left front
Benchmark HPA4 Black - left side
Benchmark HPA4 Black Rackmount - left front
Everything Audio Network 2018 Product of the Year
AV Tech Media Awards - Best Headphone Amplifier
Everything Audio Network - Stellar Sound Award
Hi-Fi News - Outstanding Product Award
The Absolute Sound - 2021 Editors' Choice Award
Home Theater and High Fidelity - Best High-End Stereo Preamplifier 2021
Home Theater and High Fidelity - Best of 2021 Award
Secrets - Reference Component Award

Benchmark HPA4 Headphone / Line Amplifier

$ 3,499.00 USD
$ 3,499.00 USD
$ 3,499.00 USD
Shipping calculated at checkout.
"Best Headphone Amplifier" - AP Mastering
"Best Preamplifier" - Secrets of Home Theater
THX-888 Headphone Amp - Benchmark Exclusive
Feed-Forward Error Correction
Relay-Controlled Volume and Input Selection
Style: Silver
Remote:
Faceplate:

SKU: 500-17200-100

Recommendations

Best High-End Stereo Preamplifier

"The Benchmark Media Systems HPA4 preamplifier is an exceptionally transparent and well-designed audio device. I found it to be an extremely neutral reference point that allowed me to hear more of what a connected speaker or headphone was actually doing and, in turn, how much my existing electronics were adding to the sound that I was hearing in my reviews."

- Carlo Lo Raso, Secrets of Home Theater and High Fidelity
Continue Reading
Home Theater and High Fidelity - Best High-End Stereo Preamplifier 2021
HPA4 Review - Sander van der Heide, Mastering Engineer

"As a headphone amplifier, the HPA4 was already a clear winner in a comparison test. More transparent, tighter, faster, quieter or less present than the HPA4 is in my opinion not possible. There was no going back. The HPA4 is the only option for my mastering setup."

- Sander van der Heide, Mastering Engineer
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Benchmark HPA4 in use at a studio.
Stereophile

"The LA4 preamplifier was the widest-bandwidth, widest-dynamic-range, lowest-noise, lowest-distortion preamplifier I had encountered at that time. . . . To those virtues, the HPA4 adds equally superb balanced and single-ended headphone outputs."

- John Atkinson
Continue Reading
stereophile recommended components 2025 award
Read more reviews

The Benchmark HPA4

The HPA4 features the Benchmark-exclusive THX-888 headphone amplifier. This is Benchmark's flagship headphone amplifier. It also marks the pinnacle of the THX headphone amplifier family. The THX-888 circuit board is manufactured by Benchmark.

Like our AHB2 power amplifier, the THX-888 features the patented THX-AAA feed-forward topology. The THX-888 keeps noise and distortion below the threshold of hearing, even when driving the most difficult headphones.

The award-winning HPA4 packs power, speed, and control into a package that includes our LA4 line-level preamplifier.

The headphone and line outputs are controlled by independent 256-step relay-switched attenuators. This is, without question, the best analog volume control system available.

HPA4 Top Internal View

Technology of the HPA4

Feed-Forward Error Correction

  • Much Faster than Feedback
  • Eliminates Zero-Crossing Distortion
  • Inherently Stable, Non-Recursive Correction
  • Stable into Any Phase Angle
  • Stable when Driving Very Low impedances
  • No Rise in THD when Driving Low Impedance Headphones
Learn More

Patented THX-AAA Technology

  • Flagship THX-888 Headphone Amplifier
  • 30 to 40 dB reduction in THD
  • Keeps THD+N Below 0 dB SPL at All Times
  • No "Electronic Fingerprints" on the Music
  • Accurate Impulse Response Into all Loads
  • 135 dB SNR
Learn More

Extended Frequency Response

  • Ultra Wide 0.1 Hz to 500 kHz Response
  • Bass is Delivered Without a Phase Shift
  • Fast, Distortion-Free Transient Response
  • Linear Phase Response
  • Accurately Reproduces the Audio Waveshape
  • Precise Rendering of Stereo Width and Depth
  • Focused 3-D Stereo Image
Learn More

Unique Features

  • High Output Current - Drives Low Impedances with Ease
  • High Output Voltage - Ample Headroom to Dive Inefficient Headphones
  • 0-Ohm Output Impedance - Maintains Tight Control of Drivers
  • Fault-Detection Circuit- Protected against Short Circuits and Overloads
  • Dual Outputs - XLR4 and 1/4" TRS
  • Independent Line and Headphone Balance Controls
Learn More

Relay-Controlled Volume

  • High-Precision Low-Impedance 256-Step Attenuator
  • Low-Noise 16-Step Input Gain Stage
  • Control Range is +15 dB to -127.5 dB in 0.5 dB Steps
  • High Precision Laser-Trimmed Thin-Film Resistors
  • 12 Relays per Output - 48 Total Including Line Outputs
  • Precision Make-Before-Break Timing - Prevents Switching Noise

Learn More

Fully-Balanced LA4 Line Amplifier

  • The HPA4 Includes all LA4 Features
  • 2 Pairs of Balanced Line Inputs
  • Fully-Balanced Differential Input Amplifiers
  • Fully-Balanced Relay-Controlled Gain Stage
  • Fully-Balanced Relay-Controlled Attenuation Stage
  • Fully-Balanced Output Line Drivers
  • Left, Right and Mono - Balanced Line Outputs
Learn More

Best of the Best

According to independent tests, the Benchmark HPA4 delivers the lowest noise and lowest distortion available from from a headphone amplifier or from a preamplifier.

The Benchmark-excusive THX-888 headphone amplifier board features the patented THX-AAA technology. This technology includes a feed-forward error correction system that reduces distortion by 30 to 40 dB. Distortion and noise are held below the 0-dB SPL threshold of hearing, even when driving the most demanding headphones.

The amplifier board is driven by a 256-step relay-controlled volume control. This system is engineered to deliver the lowest possible noise and distortion at each volume setting. A second, identical and fully-independent volume control drives the balanced and unbalanced line outputs.

The HPA4 has won many top awards and top recommendations from the press. It has received two "Product of the Year" awards, and is currently listed on Stereophile's short list of recommended components.

Benchmark HPA4 on a rustic wooden box

Listening Experience

The Benchmark HPA4 delivers a clear, open, and uncluttered playback across the entire frequency range.

Instrumental overtones are rendered with exceptional precision and realism. Vocals are reproduced with outstanding accuracy and natural tones. Transients are fast and precise. Bass is deep and well controlled.

The ultra-linear phase response of the HPA4, allows it to create a precise three-dimensional rendering of the recorded space. This space is open and uncluttered because noise and distortion are held below the 0-dB SPL threshold of hearing at all playback levels.

This experience is not limited to the headphone outputs. The HPA4 includes an LA4 preamplifier, and this is perfect match for driving Benchmark's AHB2 power amplifier.

Benchmark HPA4 with a silver front panel on a rustic wooden box

Awards

stereophile recommended components 2025 award
Home Theater and High Fidelity - Best High-End Stereo Preamplifier 2021
The Absolute Sound - Product of the Year Award
hi-fi+ 20th anniversary top 100 award
AV Tech Media Awards - Best Headphone Amplifier
Everything Audio Network 2018 Product of the Year
Hi-Fi News - Outstanding Product Award
See more awards

Front Panel

Benchmark HPA4 Front Panel View
Power
  • On/Off Momentary Switch
  • IR Remote Sensor
Display
  • Color Touch-Screen Display
  • Attenuation Shown in dB
  • Many Programmable Features
Headphone Outputs
  • 1/4" TRS Jack - Professional Grade Connector
  • XLR4 Jack - Provides the Best Output Connection
Volume Control Knob
  • Long-Life Heavy-Duty Optical Encoder
  • 0.5 dB per Step, 256 Steps
  • Push to Toggle Between Line and Headphone
  • Allows Independent or Simultaneous Control of Line and Headphones

Rear Panel

Benchmark LA4 Rear Panel View
Analog Inputs
  • Input 1 - XLR (L,R)
  • Input 2 - XLR (L,R)
  • Input 3 - RCA (L,R)
  • Input 4 - RCA (L,R)
Analog Outputs
  • Left Out - XLR
  • Right Out - XLR
  • Mono Sum Out - XLR
  • Left Out - RCA
  • Right Out - RCA
Two 12V Trigger I/O Ports
  • Bidirectional Operation
  • Work with all Single and Dual Direction Trigger Ports
  • Time Delays Allow Noise-Free System Startup and Shutdown
AC Input
  • Standard 3-Pin IEC Connector
  • Fuse Drawer with Two Fuses
  • Auto-Ranging
  • 50-60 Hz
California Proposition 65 Warning

Recommended Accessories

Additional Information

Application Notes
Videos

Product Information

HPA4 Cut Sheet

Manual

Detailed specifications and performance plots are available in the downloadable manual.

HPA4 Manual

(using balanced inputs at +24 dBu)

THX-888™ Headphone Output:

  • THD < -125 dB (0.00006%)
  • SNR > 131 dB, unweighted, 20-20 kHz
  • SNR > 135 dB, A-weighted
  • Frequency Response - 0.003 dB at 10 Hz, -0.001 dB at 20 kHz
  • - 3 dB Bandwidth exceeds 0.1 Hz to 500 kHz
  • Output Impedance, near 0 Ohms
  • Output Noise < 2.45 uV at Unity Gain, 20-20 kHz
  • Maximum Output Power, 6 Watts into 16 Ohms
  • Maximum Output Current, 1.5 A
  • Maximum Output Voltage, 11.5 Vrms into 300 Ohms
  • Crosstalk < -133 dB @ 1 kHz, -115 dB @ 10 kHz (XLR4)

Balanced Line Outputs:

  • THD < -125 dB (0.00006%)
  • SNR > 135 dB, unweighted, 20-20 kHz
  • SNR > 137 dB, A-weighted
  • Frequency Response - 0.003 dB at 10 Hz, -0.001 dB at 20 kHz
  • - 3 dB Bandwidth exceeds 0.1 Hz to 500 kHz
  • Output Impedance 60 Ohms
  • Output Noise < 1.9 uV at Unity Gain, 20-20 kHz
  • Maximum Input and Output Voltage, 20 Vrms (+28 dBu)
  • Crosstalk < -133 dB @ 1 kHz, -116 dB @ 10 kHz

Dimensions:

8.65" W x 3.88" H x 8.33" D - Including Feet

8.65" W x 3.47" H x 8.33" D - Excluding Feet

Weight:

8.0 lbs., 12 lbs. shipping

Power:

  • 18W Typical Input Power
  • 35W Maximum Input power
  • 0.33 W Standby Power (when off)
  • Internal Universal Power Supply

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