Questyle SIGMA

Product Overview

The SIGMA is a portable DAC and headphone amplifier that integrates Questyle's flagship desktop audio technology into a compact form. It features the highly acclaimed AK4493 DAC and supports high-resolution decoding up to PCM768kHz and DSD512. Its core comprises four patented PCT Current Mode Amplifier circuits in a fully discrete, fully balanced configuration, along with Questyle's proprietary TTA three-stage decoding architecture, delivering performance comparable to high-end desktop equipment. The SIGMA is triple certified by Apple MFi, Snapdragon Sound, and Sony LDAC. It includes a high-capacity battery that supports simultaneous charging and playback, catering to diverse professional audio demands.

With SIGMA, users can enjoy premium lossless audio on the go through smartphones and laptops, making Hi-Fi audio accessible anywhere. The SIGMA features both USB and high-definition Bluetooth inputs, balanced and unbalanced headphone outputs, and allows users to freely switch between IEM and headphone output modes according to their needs.

Supported Devices

Mobile Phone / Tablet / PC

Music Streamer

Earbuds / Headphones / Active Speakers

Product Components

Front Panel

The front panel features indicators for Audio Source / Status and Battery / Volume. The indicators include:

• Audio Source / Status Indicator: Displays Bluetooth, USB, Gain, Data, and IEM modes.
• Battery / Volume Indicator: Shows battery level and volume status with LEDs representing 25%, 50%, 75%, and 100%.

The main body of the device displays the internal circuitry, highlighting the USB Connection Indicator and the Four Questyle Patented PCT Current Mode Amplifiers in a Fully Discrete, Fully Balanced Design.

Side Panel

• Power Button: Press and hold for 2 seconds to turn on or off; short press to check battery level.
• Function Button: Short press to switch input source; long press to enter Bluetooth pairing mode.
• IEM / HP OUT Output Switch: A HOLD switch for output mode selection.
• Volume Button: Short press to increase/decrease volume by 1; long press to increase/decrease volume continuously.
• Gain Switch: Selects between HIGH and STD gain modes.

Bottom View

The bottom view shows connection ports:

• USB DAC IN
• ANALOG OUT (3.5mm Analog Out)
• 4.4mm BAL Analog Out
• CHARGE IN 5V/2A (Independent USB Charging Port, supports charging while in use)

LED Indicators

Controls and Functions

USB DAC Input

Connect SIGMA's USB DAC input to an iPhone, tablet, or Android phone using a Type-C to Type-C cable, or connect to a PC using a Type-A to Type-C adapter. Press the Function button to set the indicator to "USB". The "USB" LED will light up in amber.

Bluetooth Operation

Press the Function button to set the indicator to "BLUETOOTH". When the Bluetooth indicator flashes quickly, SIGMA enters pairing mode. On your phone, search for "SIGMA" in the Bluetooth list and tap to pair. The LED will stay solid to indicate a successful connection. If the indicator flashes slowly, SIGMA is not connected. Long press the Function button to start pairing. The "BLUETOOTH" LED will display amber.

Gain Control of Headphone Amplifier

There are two Gain control options:

• HIGH: For high gain mode, used to drive high-impedance devices. In HIGH mode, the GAIN LED shows red.
• STD: For standard mode, used to drive devices of high sensitivity and low impedance. In STD mode, the GAIN LED shows amber.

IEM / HP OUT Output Indicator

Output Mode Options:

• IEM Mode: For low-impedance, high-sensitivity devices. In IEM mode, the IEM LED shows amber.
• HP OUT Mode: For high-impedance, low-sensitivity devices. In HP OUT mode, the IEM LED is off.

Volume & Battery Indicators

Volume Indicator

Short press the "+/-" button to adjust the volume step by step; long press to adjust continuously. There are 4 volume indicator LEDs from left to right: 25%/50%/75%/100%. Each LED contains 16 micro-steps, for a total of 64 volume levels.

Battery Indicator

When powered on, press the POWER button to display the current battery level for 5 seconds:

• 76%-100%: 4 LEDs on
• 51%-75%: 3 LEDs
• 26%-50%: 2 LEDs
• 1%-25%: 1 LED

Charging

• 5V / 2A input via USB charging port.
• Charging LED blinks amber while charging.
• Leftmost LED blinks rapidly when battery is low; please recharge.
• Supports simultaneous playback while charging.

For Windows XP/Vista/7/8 users, to enable UAC 2.0 functionality, a driver must be installed. Please visit the Questyle website for driver download and installation instructions: www.questyle.com

Technical Specifications

• USB Playback: Max PCM Decoding: PCM768kHz/32bit, DSD Native:DSD64,DSD128, DSD256,DSD512, DSD Dop:DSD64,DSD128,DSD256. UAC 2.0 supported.
• Supported system: Win XP/Vista/Win7/Win8/Win10/Win11/, Linux/Android/HarmonyOS/macOS and iOS.
• BLUETOOTH: Supports SBC/AAC/aptX/aptX HD/LDAC decoding.
• Max. Output Power: 1200mW@32Ω Balanced.
• THD+N: <0.0003% @20mW, 300Ω.
• Line Out: Single Ended: >2.5V, Balanced: >6.8V.
• SNR: 120dB.
• Battery Life: >12h.

Package Contents

• SIGMA x1
• User Manual x1
• Warranty Card x1
• Type-A to Type-C Adapter x1
• Type-C to Type-C Cable x1
• Type-C Charging Cable x1

Contact Information

Questyle Audio Technology Co.,Ltd.

Address: Room 13A, Floor 13, Yunsong Building, Tairan 8th Road, Futian District, Shenzhen, China, 518040

Phone: +86-755-8283-5670 | +86-755-8284-0732

Email: info@questyle.com

Questyle reserves the right of final interpretation for this product. Design and specifications are subject to change without notice.

Questyle Audio Technology Co., Ltd. reserves the rights of final interpretation of this product. Design and parameters are subject to change without prior notice.

www.questyle.com