The Head Box S2 New is a compact analogue headphone amplifier: one RCA input, two front headphone sockets (6.3 and 3.5 mm) that work together, and 725 mW into 32 ohms to drive demanding headphones as well.
Head Box S2 New: outputs and connections
The headphone outputs on laptops and smartphones seldom have the current a hi-fi headphone needs. That is the job of the Head Box S2: it takes the signal from a source at its RCA input and feeds the headphones with 725 mW into 32 ohms, 11 dB of gain and an output impedance below 1 ohm. The Italian distributor rates it for headphones from 8 to 600 ohms.
There are two sockets on the front: a 6.3 mm jack for traditional hi-fi headphones and a 3.5 mm mini-jack for more recent headphones and earphones. Both are live at once, so two people can listen. Round the back, next to the input, an RCA loop output passes the signal on to another amplifier, so the unit slots in between source and system.
The case is an aluminium and metal sandwich that shields the circuits from vibration and electromagnetic interference, and low-noise parts are used throughout. Frequency response runs from 20 Hz to 80 kHz within 0.02 dB, with distortion plus noise of 0.002 %. Power is external, 5 V at 0.5 A, and standby draw stays under 0.1 W; as a later step Pro-Ject names the Accu Box S2 and Accu Box S2 USB supplies.
Specifications
- Type: analogue headphone amplifier
- Crosstalk: 68 dB
- Signal/noise: -110 dBV
- Output power: 725 mW into 32 ohms
- Gain: 11 dB
- Distortion plus noise: 0.002 %
- Bandwidth: 20 Hz to 80 kHz (±0.02 dB)
- Input: one pair of RCA sockets
- Headphone outputs: 6.3 mm jack and 3.5 mm mini-jack, both live together
- Headphone output impedance: below 1 ohm
- Loop output: one pair of RCA sockets
- Power: external, 5 V DC at 0.5 A
- Standby consumption: under 0.1 W
- Weight: 365 g, power supply excluded
- Size (width x height x depth): 103 x 37 x 120 mm
- Finishes: black, silver
