Overview: The HiFiMAN EF-2A is a hybrid USB headphone amplifier which
combines vacuum tube sound quality with solid-state technology to deliver
outstanding audio performance. The EF-2A has two inputs on the rear panel: a
line-level CD input and a USB input. On the front, you'll find a 1/4" headphone
jack, power switch, source switch (CD or USB), and rotary volume control. The
EF-2A has a simple, but elegant, brushed aluminum faceplate and chassis.
Vacuum Tubes: The EF-2A uses two 6AK5 vacuum tubes (equivalent to the
Chinese 6J1) at the input stage to significantly improve the condition of the
source signal. The tubes have a flat frequency response and a high signal
accuracy. The tubes are packed separately inside the box, so you will need to
install them through the provided holes in the acrylic top panel. When
installed, the tubes protrude approximately an inch.
Burr-Brown DAC: The EF-2A's USB input incorporates a Burr-Brown
PCM2702E DAC (digital-to-analog converter) to improve the audio performance from
your computer's headphone output. The DAC provides 16-bit/44kHz resolution,
which is equivalent to CD quality.
Power Supply: The EF-2A uses an external power supply instead of one
that is built-in. This keeps the size of the headphone amp small, and prevents
noise generated by the power supply out of the chassis.
- Volume Control: ALPS potentiometer
- USB DAC Chip: Burr-Brown PCM2702E
- Vacuum Tubes: Chinese 6J1 x2 (6AK5)
- OP-amp: OPA2604
- Input Impedance: 47k Ohms
- Output Impedance: 32-300 Ohms
- Output: @32 ohms: 3 V, 320 mW; @150 ohms: 6.2 V, 256 mW
- Frequency Response: 20 Hz to 20k Hz (+/- 0.2 dB)
- Signal-to-Noise Ratio: 95dB
- Distortion: 0.2%
- Power Consumption: <15W
- Input Voltage: 16 volts AC, 500 mA
- Power Supply: 110/220 Volts
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