Headphones amplifiers — Allnic Audio HPA-300B

The Allnic Audio HPA-300B is a valve amplifier that designer Kang Su Park created to serve two roles in one chassis - a headphone amplifier and a low-power integrated amplifier for loudspeakers. It reached the market in 2025 with a US price of USD 13,200 and a UK price of GBP 12,600. Unlike the transformerless HPA models, it uses tube rectification and couples its output stage to the load through transformers.

Key specs that matter

A pair of 300B triodes forms the output stage, the 6DR7 (or its 13DR7 sibling) handles gain and driving, and a 5U4GB rectifies the supply, with GZ34 and 5AR4 types accepted as substitutes. Rated output is 8 W per channel, and voltage gain is +28 dB. Allnic quotes 20 Hz to 20 kHz within 0.5 dB, distortion below 0.1% at 1 kHz and 1 V, and 90 dB signal-to-noise (CCIR). Sources connect through three RCA pairs and two XLR pairs, with a maximum input level of 3 V RMS. On the front sit two 6.3 mm jacks and two four-pin XLR headphone sockets, while the rear carries banana terminals for 4 and 8 ohm speakers. The unit measures 430 x 420 x 240 mm, weighs 23.64 kg and draws 168 W from the mains.

Engineering and use context

Headphones and loudspeakers share the same amplifier circuit, so both receive the same output. Allnic designs and winds its transformers in-house on nickel permalloy cores, and the maker says the output transformers here are smaller than those of its regular integrated amplifiers for faster response into headphones. Bias is set automatically, and two analogue meters show its state per channel, with needle deflection warning that a valve needs replacing. Volume runs through a motorised 61-step constant impedance bridged-T attenuator that holds a steady 10 kohm, and a small rotary switch picks the input. Valve sockets rest in a semi-liquid rubber compound against microphonics, clear cylinders surround the valves, and the rectifier housing contains a mu-metal mesh. An aluminium remote handles volume, input and mute.

Pairing

A mute button disables the speaker terminals for private listening, as plugging in headphones does not cut them automatically, and there is no separate headphone level trim. The modest power makes high-efficiency speakers the right partners. In North America the amplifier can be ordered with a RAAL Direct Drive output for ribbon headphones at no extra cost.

Alternatives

The Allnic Audio HPA-10000 OTL/OCL is the transformerless headphone amplifier and line preamplifier of the same range.