Fostex HP-A4 BL Balanced USB DAC + Headphone Amp

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The Fostex HP-A4BL builds on the original HP-A4 by adding some extra features for the budget conscious but demanding headphone user. 

Balanced and powerful in a small pacakge

The HP-A4BL, as the BL suggests, adds a 4-pin balanced output for optimum performance with high-end headphone models. Being mains powered (the HP-A4 use USB bus power only), the HP-A4BL has over 3x more output power, to handle more demanding loads, with a plus 10dB high/low gain switch for better matching.

New chip set for higher resolution formats

The Fostex HP-A4BL implements the Burr-Brown PCM1792A DAC chip, increasing file support to include 192/24 bit PCM and DSD 11.2Mhz (DSD256/Quad). The HP-A4BL can be used with the Fostex Audio player to decode FLAC, ALAC, DSD, WAV, AIFF and most other popular audio formats.

Main Features

  • Equipped with 4-pin XLR balanced output
  • Newly developed audio-grade capacitor
  • Highly precise clock crystal with low phase noise
  • Playback of 24bit/192kHz PCM and 11.2MHz DSD audio
  • High performance DAC (Burr-Brown PCM1792A) is equipped
  • Asynchronous transfer up to 192kHz/24bit compatible with USB Audio 2.0
  • HI/LO Gain selection (10dB) for wider selection of headphones
  • Digital Filter selecting roll-off characteristics and cut-off frequencies  



[USB] terminal

  • Interface :USB 2.0 Hi Speed
  • Sampling Frequencies :PCM 44.1kHz, 48kHz,
  • 88.2kHz, 96kHz, 176.4kHz, 192kHz DSD 2.8MHz,
  • 5.6MHz, 11.2MHz
  • Quantization :16bit, 24bit

[Digital In]

  • Connector :Optical, Square
  • Format :S/PDIF
  • Sampling Frequencies :44.1kHz, 48kHz, 88.2kHz,
  • 96kHz, 176.4kHz, 192kHz
  • Quantization :16bit, 24bit



  • Connector :XLR (4-pin)
  • Maximum output :300mW or more (32 ohm)
  • Load impedance :16 - 600 ohm
  • THD :less than 0.04% (at 1kHz)
  • Frequency Response :20Hz - 80kHz (+-3dB, 32 ohm, 100mW)


  • Connector :1/4" stereo jack
  • Maximum output :300mW or more (32 ohm)
  • Applicable load impedance :16 - 600 ohm
  • THD :less than 0.04% (at 1kHz)
  • Frequency Response :20Hz - 80kHz (+-3dB, 32 ohm, 100mW)


  • Connector :RCA Pin
  • Reference output level :2Vrms (0 dBFS)
  • Applicable load impedance :less than 10k ohm
  • THD :less than 0.01% (at 1kHz)
  • Frequency Response :20Hz - 80kHz (+-3dB)


  • Connector :Optical (square)
  • Format :S/PDF
  • Frequency Response :44.1kHz, 48kHz, 88.2kHz, 96kHz, 176.4kHz, 192kHz
  • Quantization :16, 24bit
  • [microSD] card slot (for firmware upgrade only) Format: FAT32 Compatible card: microSD card (SDHC), up to 32GB
  • Accessories :Rubber foot (x4), USB cable, Manual, AC adapter
  • Power supply :DC12V
  • Measurements :150(W) x 34(H) x 157(D)mm including protrusion
  • Weight :approx. 630g

Delivery and Returns

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DAC Specification

Headphone Amplifier:

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