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DACs — Questyle SIGMA Pro
Description, images, technical data and specifications
Questyle SIGMA Pro
Image source — © Questyle
The SIGMA Pro is a portable DAC with headphone amplifier from Questyle, released alongside the plainer SIGMA and positioned by the maker as the professional version of the pair. It combines USB, optical, coaxial and Bluetooth reception with analogue inputs, three headphone sockets and a battery in one aluminium body, so it can serve a phone, a laptop or a desk system. Questyle lists it in the US at USD 899, with black and silver colour options.
Key specs that matter
Two ESS ES9069 chips in a dual-mono array do the conversion, fed by an XMOS XU316 USB receiver. PCM is accepted up to 768 kHz and DSD up to DSD512, with full MQA unfolding. Questyle quotes distortion as low as 0.0002 percent under load. Outputs are a 3.5 mm single-ended jack, a 4.4 mm balanced jack and a 6.35 mm jack, with manual gain selection. On the input side there are 3.5 mm and 4.4 mm balanced analogue sockets, optical and coaxial digital, and USB. The body measures 155.7 by 85 mm and weighs about 330.8 g.
Engineering and use context
The analogue section follows the fully balanced layout that Questyle builds its products around, using four sets of the company's patented fully discrete current-mode amplifier stages rather than an op-amp headphone chip. The analogue inputs are there for more than line playback - the maker lists recording and monitoring among the unit's functions, which lets it sit between another source and a recorder. Wireless reception runs over Bluetooth 5.4 with certification for both Qualcomm Snapdragon Sound and Sony LDAC, and the unit carries Apple MFi certification for direct use with iPhone and iPad. Two USB-C ports split the jobs, one carrying data and the other charging, so the battery can be topped up while music plays. The 4300 mAh cell is rated for up to 12 hours on one charge. A small LCD screen shows status, and the chassis is machined from aviation-grade aluminium with a Kunlun glass panel.
Pairing
The choice of three jack sizes means single-ended IEMs, balanced cables and full-size studio headphones can all be used without adapters. At home a CD transport or TV can feed the optical or coaxial socket, while on the move a phone connects either by cable or over LDAC. Owners who use the recording path would connect the analogue inputs to a portable player or mixer.
Alternatives
The Questyle SIGMA shares the chassis concept and battery but uses an AKM AK4493 converter and has no full-size headphone socket.
Key specs that matter
Two ESS ES9069 chips in a dual-mono array do the conversion, fed by an XMOS XU316 USB receiver. PCM is accepted up to 768 kHz and DSD up to DSD512, with full MQA unfolding. Questyle quotes distortion as low as 0.0002 percent under load. Outputs are a 3.5 mm single-ended jack, a 4.4 mm balanced jack and a 6.35 mm jack, with manual gain selection. On the input side there are 3.5 mm and 4.4 mm balanced analogue sockets, optical and coaxial digital, and USB. The body measures 155.7 by 85 mm and weighs about 330.8 g.
Engineering and use context
The analogue section follows the fully balanced layout that Questyle builds its products around, using four sets of the company's patented fully discrete current-mode amplifier stages rather than an op-amp headphone chip. The analogue inputs are there for more than line playback - the maker lists recording and monitoring among the unit's functions, which lets it sit between another source and a recorder. Wireless reception runs over Bluetooth 5.4 with certification for both Qualcomm Snapdragon Sound and Sony LDAC, and the unit carries Apple MFi certification for direct use with iPhone and iPad. Two USB-C ports split the jobs, one carrying data and the other charging, so the battery can be topped up while music plays. The 4300 mAh cell is rated for up to 12 hours on one charge. A small LCD screen shows status, and the chassis is machined from aviation-grade aluminium with a Kunlun glass panel.
Pairing
The choice of three jack sizes means single-ended IEMs, balanced cables and full-size studio headphones can all be used without adapters. At home a CD transport or TV can feed the optical or coaxial socket, while on the move a phone connects either by cable or over LDAC. Owners who use the recording path would connect the analogue inputs to a portable player or mixer.
Alternatives
The Questyle SIGMA shares the chassis concept and battery but uses an AKM AK4493 converter and has no full-size headphone socket.
Specifications
Model name
SIGMA Pro
Conversion type
N/A
Engine
ESS9069 DAC
DSD compatability
Yes
Parameters
up to PCM 32 bit / 768kHz and DSD512
Frequency response low +/- 3dB (Hz)
N/A
Frequency response high +/- 3dB (Hz)
N/A
Gain (dBu)
N/A
Output Level (balanced) (V)
N/A
Output Level (single-ended) (V)
N/A
Input Impedance (balanced) (Ω)
N/A
Input Impedance (single-ended) (Ω)
N/A
Output Impedance (balanced) (Ω)
N/A
Output Impedance (single-ended) (Ω)
N/A
Analog outputs
N/A
Signal to Noise Ratio (dB)
N/A
Total Harmonic Distortion + Noise (% at 22 kHz)
0.0002
Dimensions (mm)
N/A
Weight (kg)
N/A
Official link
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Questyle SIGMA