Fostex HP-A4 24-Bit USB DAC Headphone Amplifier

Special Price $399.99 Regular Price $499.99
Ships in 10-14 business days

$0.00 Tax Outside NJ


  • Up to 24-Bit/192kHz PCM Support
  • Up to 5.6MHz DSD Support
  • USB 2.0 Input
  • Optical S/PDIF Digital I/O
  • Front-Panel 1/4" Headphone Output
  • 2 Gain-Staging Levels
  • Selectable Filter
  • Mac & Windows Compatible
  • Includes USB Cable & Rubber Feet
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The HP-A4 24-Bit USB DAC Headphone Amplifier from Fostex supports PCM audio up to 24-bit/192kHz and DSD audio up to 5.6MHz. It features a front-panel 1/4" stereo headphone output, rear-panel stereo RCA outputs, and optical S/PDIF I/O. The HP-A4 has 2 gain staging levels, allowing you to boost the output of the amp by 10dB without needing to touch the volume knob. The selectable filter allows you to cut-off lower frequencies if desired. A USB cable and 4 rubber feet are included.

USB bus powered

Linear PCM audio up to 24-bit/192 kHz and DSD audio up to 5.6 MHz playback

High-resolution playback in combination with "FOSTEX Audio Player" software

HI/LO Gain selection (10 dB)

Asynchronous transfer mode using custom-made crystal

Digital filter with selectable roll-off and cut-off characteristics

Complies with USB Audio Class 2.0 on Windows XP (SP2 or later), Vista, 7, 8 and Mac OS X 10.6 or later

microSD (SDHC) card drive on the rear panel for future firmware updates


More Information
Stock StatusShips in 10-14 business days
Mfr Part NoAMS-HP-A4
Upc Number636827304221


Sampling Frequency

Up to 192 kHz (PCM)
Up to 5.6 MHz (DSD)

Bit Depth

Up to 24-bit


1x USB high speed
1x S/PDIF TOSlink (16/24-bit, 44.1 to 192 kHz)



1x 1/4" (6.3 mm) stereo headphone output
2x analog RCA outputs
1x S/PDIF TOSlink (16/24-bit, 44.1 to 192 kHz)

Maximum Output

100 mW (32 Ω loaded)
RCA Outputs: 2 Vrms reference output level


Headphone Output: Less than 0.04% at 1 kHz, 32 Ω loaded, 100 mW
RCA Outputs: Less than 0.01% at 1 kHz

Frequency Response

20 Hz to 80 kHz +/-3dB (1 kHz, 32 Ω loaded, 100 mW, FS 192 kHz)
RCA Outputs: 20 Hz to 80 kHz +/-3 dB (at FS 192 kHz)


SD Card Slot

1x microSD slot (for firmware updates)


Windows: XP (SP2 or later), Vista, 7, 8
Mac: OS X 10.6 or later


USB bus powered

Power Consumption

2.5 W

Dimensions (W x H x D)

4 x 1 x 6" (113 x 34 x 155 mm), excluding protruded parts


17 oz (500 g), approximate


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