Pro-Ject Head Box DS3 B
Fully balanced headphone amplifier from Pro-Ject, featuring multiple outputs (3.5, 6.3, 4.4 mm and XLR) and an aluminium chassis, for discerning headphone enthusiasts.
Description
The Head Box DS3 B is a headphone amplifier from Pro-Ject, built around a fully balanced, discrete topology. It is intended for headphone listening requiring dedicated amplification, capable of driving a wide range of transducers thanks to several standard outputs.
Its output power varies according to the impedance of the connected headphones: 510 mW at 8 ohms, 900 mW at 16 ohms, 1500 mW at 32 ohms and 560 mW at 300 ohms. This distribution ensures a sufficient power reserve both with low-impedance headphones and with more demanding models requiring higher voltage. The total harmonic distortion remains very low, below 0.002% at 1 kHz for a 500 mV input, and the signal-to-noise ratio exceeds 118 dB A-weighted at 1 kHz, which limits perceptible background noise through the headphones. Crosstalk is kept below -83 dB at 10 kHz, an important factor for stereo imaging precision when listening on headphones. Gain differs depending on the input used: 12 dB via the RCA input, 6 dB via the XLR input.
In terms of connectivity, the unit offers an analogue RCA input and an XLR input, as well as an RCA loop output allowing another device to be connected in parallel. The headphone outputs cover the most common formats: 3.5 mm and 6.3 mm jacks, as well as balanced 4.4 mm and 4-pin XLR connectors, allowing the use of balanced headphone cables to make full use of the unit's differential design. The minimum accepted headphone impedance is 8 ohms.
This model is intended for stationary use, in an office or living room, for extended headphone listening sessions with hi-fi sources featuring RCA or XLR outputs. The presence of a balanced output rounds out the profile for users equipped with high-end headphones supplied with a 4.4 mm or XLR balanced cable.
Technical specifications
| Maximum output power | 510 mW / 8 ohms, 900 mW / 16 ohms, 1500 mW / 32 ohms, 560 mW / 300 ohms |
| Headphone output | Balanced 3.5 mm, 6.3 mm and 4.4 mm connectors, 4-pin balanced XLR |
| Signal to noise ratio | > 118 dB A-weighted at 1 kHz |
| Total harmonic distortion | < 0.002% at 1 kHz at 500 mV input |
| Crosstalk | < -83 dB at 10 kHz |
| Gain | 12 dB / 6 dB (RCA input / XLR input) |
| Frequency response | < -0.2 dB at 20 Hz - 20 kHz |
| Analogue inputs | 1 pair RCA/Cinch, 1 pair XLR |
| Analogue loop outputs | 1 pair RCA |
| Headphone impedance | min. 8 ohms |
| Power supply | 18 V/1 A DC, 110-240 V, 50/60 Hz |
| Standby power consumption | < 0.5 W |
| Dimensions (H × W × D) | 206 x 70 x 194 (218) mm |
| Weight | 1,430 g without power supply |
What to check before buying used
On this balanced headphone amp, systematically test all four outputs (3.5 mm, 6.3 mm, 4.4 mm and 4-pin XLR) as well as the RCA and XLR inputs, checking for loose contacts or crackling at the connectors. Also check that the volume potentiometer functions correctly throughout its full range, as crackling or a dead spot would indicate wear on the resistive track. Finally, check the condition of the original external 18 V power supply, as its absence or replacement with a non-compliant model may affect the stated performance.
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