Headphones amplifiers — Allnic Audio ASRA / RHPA-7500

The ASRA / RHPA-7500 is a valve amplifier from Allnic Audio of South Korea that drives headphones and loudspeakers from one chassis. Allnic sells it under the ASRA name and announced it in April 2026. In the United Kingdom the standard version costs GBP 5,900, and the version fitted with the optional Constant Impedance Attenuator costs GBP 7,200.

Key specs that matter

Each channel delivers 20 W with its output valves working as pentodes or 10 W after a switch to triode operation. Voltage gain is +24 dB in pentode mode and +22 dB in triode mode, and the input accepts up to 4 V RMS. The valve complement is two ECF tubes, two 12AU7 double triodes and four 7558 beam pentodes. Allnic quotes a flat frequency response from 20 Hz to 20 kHz, 0.1% THD at 1 kHz with 1 V out, plus -85 dB (IEC) for signal-to-noise. Headphones between 10 and 300 ohm form the optimum load range. The case measures 355 mm wide, 445 mm deep and 140 mm high, the net weight is 12.0 kg, and power consumption is 80 W.

Engineering and use context

Allnic hand-winds the output transformers on nickel-based Permalloy cores made for the ASRA amplifiers. Switching between pentode and triode operation changes both the power and the output impedance of the amplifier. Line sources plug into three single-ended RCA pairs or one balanced XLR pair. The front offers a 1/4 inch TRS jack for single-ended headphones and a 4-pin female XLR for balanced cables. A third output, a 4-pin male XLR, feeds a dedicated circuit for RAAL ribbon headphones such as the SR1a and CA-1a, which then run directly from the amplifier without the separate interface box these models otherwise need. A pair of binding posts on the rear turns the unit into a small integrated amplifier for loudspeakers. Volume is set by a precision potentiometer as standard, while the CIA option replaces it with a 41-step attenuator.

Pairing

The wide impedance window covers most dynamic and planar headphones, and owners of RAAL ribbon models gain a direct connection that otherwise calls for an adapter. With several line inputs and a balanced one, a DAC, a streamer and a phono preamp can share the amplifier without a separate preamp. For the speaker terminals, efficient loudspeakers are the sensible match, as a few watts of valve power leave little reserve for difficult loads.

Alternatives

Allnic also builds the HPA-300B, a valve headphone amplifier with 300B output tubes.