Headphones amplifiers — Allnic Audio HPA- 5000 XL

The Allnic Audio HPA-5000 XL is a stereo valve headphone amplifier by Allnic Audio and the XL version of its HPA-5000. Allnic fitted the XL with a revised power transformer. The circuit has neither an output transformer nor an output capacitor, so the valves drive the headphones directly. In the UK the XL was priced at GBP 7,000, and in the eurozone at EUR 8,500.

Key specs that matter

Allnic rates the amplifier at a maximum output of 5 W in pure Class A, with a voltage gain of +28 dB. Response is flat from 20 Hz to 20 kHz within 0.3 dB, total harmonic distortion stays under 0.03%, and noise sits 68 dB below the signal (CCIR, 1 kHz). Eight valves are fitted - four 7233 triodes, two E180CC double triodes and two 6AN8 valves, all supplied as new old stock. Sources connect through one pair of RCA inputs or one pair of balanced XLR inputs, and there are two headphone outputs, a 6.35 mm jack and a four-pin balanced XLR socket. The unit weighs about 9 kg.

Engineering and use context

The topology is output transformer-less (OTL) and output capacitor-less (OCL), and the signal path is a true balanced circuit in which the positive and negative halves cancel each other. Level is set by a 41-step attenuator with single silver contacts rather than a carbon track or a digital chip, and Allnic states that channel balance stays at 0 dB across the whole volume range. Every valve stands in an Absorb GEL socket, a vibration damper patented by Allnic, and is covered by its own chimney. A tube extractor comes in the box. Two bias meters sit on the chassis, and each setting is adjusted with a small screwdriver. The aluminium casework has a lightly brushed finish in silver or black, and the amplifier is built to the EU RoHS regulation on hazardous substances.

Pairing

Allnic recommends dynamic headphones from 30 to 600 ohm, while the designer tuned the circuit for low-impedance models in the 30 to 50 ohm region. Headphones with a balanced four-pin cable get the full benefit of the balanced circuit, and a DAC fitted with XLR sockets lets the whole chain from source to headphone stay differential. There is no digital input or built-in DAC, so a streamer or computer needs an external converter in front of the amplifier.

Alternatives

The Allnic HPA-10000 XL is the higher-power headphone amplifier of the range, with a 61-step constant-impedance attenuator in place of the 41-step unit.