Усилители для наушников — Pro-Ject Head Box E

The Head Box E is a micro-sized headphone amplifier made by Pro-Ject Audio Systems, intended to drive headphones from laptops, smartphones and other modern sources that lack a capable output of their own. Instead of relying on integrated amplifier chips, Pro-Ject built the circuit as a fully discrete design, and it sits in an all-metal enclosure whose machined aluminium fascia comes in silver or in black.

Key specs that matter

Pro-Ject rates the output at 665 mW into 32 ohm, and the output impedance stays below 1 ohm, so the amplifier is meant to cope with demanding headphones as well as easy ones. Gain is 11 dB. The published frequency response runs from 20 Hz to 80 kHz within 0.02 dB, THD plus noise stays under 0.005 percent, noise sits 105 dBV down and crosstalk is 65 dB. The case measures 103 x 37 x 120 mm and weighs 390 g, power adapter excluded.

Engineering and use context

The input side consists of one RCA pair for line-level analogue signals. On the front there are two headphone sockets, a 6.3 mm jack and a 3.5 mm jack, and both work simultaneously, letting a pair of listeners use one source together. A second pair of RCA sockets acts as a loop output that passes the incoming signal straight through to another amplifier, letting the Head Box E sit in a chain without taking over the only line output of a DAC or preamplifier. Power arrives from an external 5 V supply rated at 0.5 A, and standby consumption stays below 0.5 W. Pro-Ject points to low distortion and low noise components throughout the circuit, and the solid metal housing keeps the small footprint rigid on a crowded desk or shelf.

Pairing

Because the unit has no digital input, a phone or computer needs a separate DAC with an RCA line output ahead of it, and one of the compact Box-series DACs from the same maker fits the identical case width. The loop output makes it easy to keep a stereo power amplifier connected to the same source, with the headphone amplifier simply tapping the signal on its way through. The low output impedance suits both low-impedance portable models and higher-impedance studio headphones, and the dual sockets allow a full-size pair and an in-ear pair to stay plugged in side by side.

Alternatives

The Pro-Ject Head Box S2 is another fully aluminium headphone amplifier from the same Box range, rated at up to 725 mW and offering the same 3.5 mm and 6.35 mm outputs with an RCA loop out.