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DACs — Questyle SIGMA
Description, images, technical data and specifications
Questyle SIGMA
Image source — © Questyle
The SIGMA is a pocket-sized Bluetooth DAC and headphone amplifier from Questyle of Shenzhen, China, released in late October 2025 at USD 599, EUR 599 or GBP 529. It shares its launch with the SIGMA Pro, which followed in early November, and it is the simpler of the pair - it takes a digital signal only over USB or Bluetooth and has no analogue input or recording function.
Key specs that matter
A single AKM AK4493 chip does the conversion inside the maker's own TTA decoding architecture. PCM is accepted up to 32 bit and 768 kHz, DSD natively from DSD64 to DSD512, and the unit is listed as MQA compatible. The balanced output delivers 1,200 mW into 32 ohm, and Questyle quotes a peak output above 5 W with a peak current of 3 A. THD+N is below 0.0002% at 20 mW into 300 ohm, signal to noise is 120 dB, and the company measured a noise floor of -130 dB in its own lab. Headphones plug into a 3.5 mm single-ended jack or a 4.4 mm balanced socket. The same sockets work as line outputs at more than 2.5 V unbalanced and more than 6.8 V balanced. The casing weighs 164 g.
Engineering and use context
Amplification comes from four sets of patented Current Mode Amplifier circuits, built fully discrete and fully balanced rather than from an integrated op-amp output stage. Wireless reception uses a Qualcomm chip with Bluetooth 5.4, carries both Snapdragon Sound and LDAC certification, and supports LDAC, aptX Adaptive, aptX HD, standard aptX, AAC, SBC and LE Audio. Two USB-C ports keep data and charging apart, so a phone does not have to power the amplifier during playback, and the USB side works as a UAC 2.0 device with Apple MFi certification. Compatible hosts include iOS, Android 5.1 and newer, Windows 10 version 1803 onward, macOS, HarmonyOS and Linux. The 3.7 V battery runs for over 12 hours and recharges in about 3.5 hours at up to 2 A from a 5 V supply, and the unit keeps playing while it charges. A dedicated IEM mode gives 64 volume steps, and standard and high gain settings sit alongside it. The body is CNC-machined aluminium with a coating to suppress radio interference, topped by optical-grade glass with LED accents.
Pairing
Fine volume steps in IEM mode make low-impedance in-ear monitors easy to set, and the balanced socket with high gain is the route for full-size headphones that need more voltage. In line-out mode an unbalanced-to-RCA lead or a balanced-to-XLR lead feeds a home amplifier or powered monitors, turning the SIGMA into a compact source for a desk or living room system.
Alternatives
The Questyle SIGMA Pro uses dual ESS ES9069 chips in a dual-mono layout and adds optical, coaxial and analogue inputs with recording, plus a 6.35 mm jack, at USD 899.
Key specs that matter
A single AKM AK4493 chip does the conversion inside the maker's own TTA decoding architecture. PCM is accepted up to 32 bit and 768 kHz, DSD natively from DSD64 to DSD512, and the unit is listed as MQA compatible. The balanced output delivers 1,200 mW into 32 ohm, and Questyle quotes a peak output above 5 W with a peak current of 3 A. THD+N is below 0.0002% at 20 mW into 300 ohm, signal to noise is 120 dB, and the company measured a noise floor of -130 dB in its own lab. Headphones plug into a 3.5 mm single-ended jack or a 4.4 mm balanced socket. The same sockets work as line outputs at more than 2.5 V unbalanced and more than 6.8 V balanced. The casing weighs 164 g.
Engineering and use context
Amplification comes from four sets of patented Current Mode Amplifier circuits, built fully discrete and fully balanced rather than from an integrated op-amp output stage. Wireless reception uses a Qualcomm chip with Bluetooth 5.4, carries both Snapdragon Sound and LDAC certification, and supports LDAC, aptX Adaptive, aptX HD, standard aptX, AAC, SBC and LE Audio. Two USB-C ports keep data and charging apart, so a phone does not have to power the amplifier during playback, and the USB side works as a UAC 2.0 device with Apple MFi certification. Compatible hosts include iOS, Android 5.1 and newer, Windows 10 version 1803 onward, macOS, HarmonyOS and Linux. The 3.7 V battery runs for over 12 hours and recharges in about 3.5 hours at up to 2 A from a 5 V supply, and the unit keeps playing while it charges. A dedicated IEM mode gives 64 volume steps, and standard and high gain settings sit alongside it. The body is CNC-machined aluminium with a coating to suppress radio interference, topped by optical-grade glass with LED accents.
Pairing
Fine volume steps in IEM mode make low-impedance in-ear monitors easy to set, and the balanced socket with high gain is the route for full-size headphones that need more voltage. In line-out mode an unbalanced-to-RCA lead or a balanced-to-XLR lead feeds a home amplifier or powered monitors, turning the SIGMA into a compact source for a desk or living room system.
Alternatives
The Questyle SIGMA Pro uses dual ESS ES9069 chips in a dual-mono layout and adds optical, coaxial and analogue inputs with recording, plus a 6.35 mm jack, at USD 899.
Specifications
Model name
SIGMA
Conversion type
N/A
Engine
AKM AK4493
DSD compatability
Yes
Parameters
up to 32 bit / 768 kHz 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)
N/A
Dimensions (mm)
N/A
Weight (kg)
N/A
Official link
