A compact powerhouse with serious control
The Yulong A39 is a Class-A headphone amplifier and reference-grade preamp that blends sophisticated tech with warm, dynamic sound. Designed to handle everything from high-impedance over-ears to sensitive IEMs, it delivers 6W of Class-A balanced power and 99-step R2R volume control in a compact, CNC-machined aluminum chassis. Paired with its retro VU meters and IPS display, it brings the brains, the brawn, and a little bit of nostalgia to your desk.
Class-A power—without the heatstroke
At the heart of the A39 is a 6W constant-current Class-A amplifier, built from discrete components and driven by 16 medium-power transistors. This means rich harmonics, low distortion (0.0002%), and serious drive—without needing a fan or a fire extinguisher. The all-aluminum case pulls double duty as a heatsink, keeping things cool even when the evening gets away from you.
Real-time monitoring and protection
Under the hood, a CPU running a custom Linux system manages thermal conditions, overcurrent protection, voltage, and startup sequences. So even if you’re swapping headphones mid-session or pushing power-hungry cans, the A39 keeps everything running safely and quietly.
Volume that doesn’t suck (your tone away)
Traditional volume pots introduce noise and lose detail. The A39 uses a CPU-controlled relay system paired with an R2R resistor ladder, giving you 99 steps of transparent, lossless attenuation. The relay locks in a closed loop, eliminating electromagnetic interference, while the R2R network keeps the signal pure.
Built to pair with the D39 DAC
The A39 is designed to visually and functionally pair with Yulong’s D39 streaming DAC. Together, they form a full desktop control center—small enough to fit on an A4 sheet, powerful enough to anchor your entire system.
Looks smart, acts smarter
The IPS LCD screen shows dynamic spectrums and classic VU meters—one eye on nostalgia, the other on precision. The intuitive knob or included remote make adjustments easy.
A power supply that doesn’t cut corners
Inside is a custom 50W NORATEL toroidal transformer with linear regulation. It feeds clean, consistent power to the amp and preamp stages, contributing to the low noise floor and stable operation.
Product highlights
- Constant-current Class-A discrete headphone amplifier with 6W balanced output
- FPGA-controlled R2R resistor network with relay switching for 99-step volume control
- CPU monitoring for voltage, current, temperature, delayed startup, and shutdown
- 50W custom NORATEL toroidal transformer with linear power regulation
- Balanced (XLR/4.4mm) and single-ended (6.35mm) headphone outputs
- Balanced (XLR) and single-ended (RCA) preamp inputs and outputs
- IPS LCD screen with real-time spectrum analyzer and retro VU meters
- Remote control and single-knob operation
- Impedance switching for headphone output
- All-aluminum CNC chassis for passive heat dissipation
- Designed to match the Yulong D39 streaming DAC
- USB DFU port for firmware and software updates
- Compact A4-sized footprint for desktop use
- Global voltage switch for international use
Specs
- Headphone output power (single-ended):
- 32Ω: 2500mW
- 64Ω: 2200mW
- 150Ω: 1000mW
- 300Ω: 500mW
- 600Ω: 250mW
- Headphone output power (balanced):
- 32Ω: 6000mW
- 64Ω: 6000mW
- 150Ω: 3200mW
- 300Ω: 1800mW
- 600Ω: 900mW
- THD+N: 0.0002%
- SNR: >120dB
- Crosstalk: <-100dB
- Frequency response: 20Hz–30kHz ±0.15dB
- Preamp input impedance: 10kΩ
- Preamp output impedance: 200Ω
- Preamp output level:
- Power consumption: <50W
- Dimensions: 9.8in x 8.3in x 2.4in (248mm x 210mm x 60mm)
- Weight: 5.7lbs (2.6kg)
