Усилители для наушников — Aune S17 Pro EVO

The S17 Pro EVO is a fully discrete, fully balanced Class A headphone amplifier from the Chinese maker Aune Audio, and it also works as a preamplifier. It updates the S17 Pro, keeping the core circuit, the twin JFET input and the balanced output stage, and adds independent switching of the headphone and preamplifier outputs, separate volume memory for each mode and automatic screen switch-off, with the component count rising from 635 to 657. The price is USD 799, against USD 699 for the S17 Pro.

Key specs that matter

The circuit has a twin JFET input and two amplifier stages, with 16 output transistors and two pairs in parallel in the final stage. Gain is 8.9 dB in low and 13.6 dB in high setting. On the balanced XLR output at high gain, the amplifier delivers 7500 mW into 32 ohm, 2673 mW into 100 ohm, 918 mW into 300 ohm and 459 mW into 600 ohm, and on the 6.35 mm output 2050 mW into 32 ohm and 117 mW into 600 ohm. Frequency response is 20 Hz to 80 kHz within 0.05 dB. THD+N is below 0.00016% on XLR and 0.0003% on 6.35 mm, and signal to noise ratio exceeds 116 dB and 115 dB. The noise floor is about 3.6 µV. Headphone output impedance is 1 ohm, the RCA and XLR preamplifier outputs have 200 and 100 ohm, and both inputs present 10 kOhm. The case measures 288 x 211 x 63 mm and is black.

Engineering and use context

Two Class A bias settings, A-L and A-H, set 50 or 100 mA per transistor, or 100 or 200 mA per channel, and the amplifier steps down automatically if its temperature reaches 69 degrees C. Higher bias keeps the output transistors conducting over a larger part of the signal swing. Volume is an electronic R2R ladder on a JRC chip, which switches precision resistors instead of using a potentiometer track. A 50 W low-ripple toroidal transformer feeds a capacitor array of 19,200 µF. Headphone outputs are 4-pin XLR, 4.4 mm balanced and single-ended, and the unit accepts RCA and XLR inputs. The low noise floor matters with sensitive in-ear monitors, while the high balanced power suits planar headphones. A colour display and a remote control are provided.

Pairing

Aune's S10N and S10 Pro network players are the intended sources, and any DAC with RCA or XLR outputs works. As a preamplifier it can drive active speakers or a power amplifier.

Alternatives

The Aune S17 Pro is the earlier version with the same circuit but without independent output switching and mode memory.