Vacuum Tube Driven Headphone Amplifier/USB DAC

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HIFIMAN EF2A Hybrid Vacuum Tube/USB DAC Headphone Amplifier

The HIFIMAN EF2A Headphone Amplifier Offers an Incredible Listening Experience

Plug the HiFiMAN EF2A into one of your computer's USB ports and prepare to be impressed. This compact digital-to-analog converter/headphone amp bypasses your computer's built-in DAC and audio circuitry — processing your digital music files outside the noisy environment of your computer for far better sound quality. The EF2A's vacuum tube headphone amplifier brings your tunes to life, imparting smoothness and clarity. You'll hear more dynamics and detail that you can really savor on your headphones. The EF2A also includes an analog audio input so you can enjoy improvements in sound with another music source. This is one component that looks so cool, you'll absolutely want to show it off on your desktop.

General Features:

  • Compact desktop headphone amplifier/DAC
  • Provides significantly more dynamics and detail to your headphones
  • Utilizes two 6J1 vacuum tubes for the amplifier input stage
    • Injects smoothness and clarity into your music to really bring it to life
  • Burr Brown PCM2702 digital-to-analog converter provides exceptional sound quality
  • Rear USB input allows you to connect to your computer and bypass the built-in DAC and audio circuitry
  • Rear stereo RCA audio input allows you to enjoy your music from other audio sources
  • Full size front stereo headphone output
  • Rotary volume control
  • Sleek, durable metal chassis
  • Acrylic top panel
  • External power supply included
  • Dimensions: 5-11/16"W x 4-1/4"D x 3-1/8"H
  • Authorized Internet Dealer
  • 1-year Manufacturer's Warranty


  • Input Impedance: 47,000 ohms
  • Output Impedance: 32-300 ohms
  • Output:
    • @ 32 Ohms: 3 v, 320 mw
    • @ 150 Ohms: 6.2 v, 256
  • Frequency Response: 20-20,000 Hz
  • Signal-to-Noise Ratio: 95dB
  • Distortion: 0.2%

What's in the Box?

  • HIFIMAN EF-2A Headphone Amplifier/DAC
  • Two 6J1 Vacuum Tubes
  • AC Power Adapter
  • 5' USB Cable
  • User Guide

Note: HiFiMAN products can only be shipped to customers in the United States

Product History:

HIFIMAN EF2C thumbnail
(newest, current model)
HIFIMAN EF-2A thumbnail
(previous model, replaced by HIFIMAN EF2C)

Headphone Amplifier Specifications

Digital-to-Analog Converter (DAC)
A Digital-to-Analog converter (also known as a DAC) converts a digital audio signal into an analog signal. This is especially helpful for listen to music from digital sources, such as iPods and smart phones.
Frequency Response
The range of frequencies the amplifier will reproduce (lowest frequency to the highest). Bigger is better, meaning the wider the range, the better. The optimal range is 20 - 20,000 Hz (which is the range of human hearing).
20 - 20000 Hz
Input Connection
This is the manner in which the headphone amplifiers receive an input audio signal.
Stereo RCA
Input Impedance
This is the input impedance of the headphone amplifier.
47000 ohms
Output Connection
This is the manner in which the headphone amplifier will output the audio signal.
1/4" Plug
Number of Outputs
Some headphone amplifiers have a built-in splitter so multiple pairs of headphones can be connected to it. The number specified here is the number of headphones that can be connected to the amplifier.
Output Power
This is the output wattage of the headphone amplifier. It is measured in mW.
320 mW
Output Impedance
This is the output impedance of the headphone amplifier.
32 ohms
The width of the item from left to right (side-to-side) measured in inches.
The height of the item, measured from top to bottom, in inches.
The front-to-rear depth of the item, in inches. If the item is angled or slanted, this value is the bottom measurement.
Amplifier Style
Some headphone amplifiers are designed to be portable and others are meant to be placed on a desk. This will tell you what style of amplifier this item is.

Specials with this Item

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Warranty and Return Policy

Parts Warranty Duration
1 year
Labor Warranty Duration
1 year
Warranty Provider

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Sonic Electronix Wiring Guide

Wiring Diagram Legend

Warning: The image depicted shows the resistance change when wiring multiple subwoofer terminals. Please refer to your subwoofer's owner's manual for the proper wiring of its terminals. Sonic Electronix, Inc. is not responsible for damage caused to your audio system or vehicle due to improper installation. Please call tech support at 1-877-289-7664 if you require additional assistance.

Product Name: HIFIMAN EF-2A

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Vacuum Tube Driven Headphone Amplifier/USB DAC


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