• Power supply to ensure excellent sound
• Features low-frequency transformer
• Uses THX AAA 788+ chips
• Can produce an undistorted 1100mW
• Can produce undistorted 2100mW under a 32 ohms load
• Ensures minimal interference between different components
• PCB of the K9 Pro ESS uses a partitioned layout
• Audio signal goes through a mammoth 6-stage circuit
• Six-stage audio circuit, to reveal every last detail
• RGB indicator lights light up differently as per sampling rate

Electricity is the mother of sound, so special attention was paid to optimize the FiiOK9 Pro ESS Desktop DAC and Amplifier’s power supply to ensure excellent sound. The FiiO K9 Pro ESS’s linear power supply, with its low-frequency transformer and 4 massive 4700uF capacitors, makes sure that the rest of the system gets abundant clean power.

THX AAA 788+ Chips

The THX AAA 788+ chips used in the FiiOK9 Pro ESS Desktop DAC and Amplifier provide exemplary details and dynamics no matter if you are using low or high-impedance headphones. The K9 Pro ESS can produce an undistorted 1100mW as tested in FiiO Labs under balanced out under a 300 ohms load, and an undistorted 2100mW under a 32 ohms load, 50 percent higher than the original THX AAA 788 amplifier chips.

Precise Design

Fully differential signals go through the DAC, volume adjustment, and amp for a truly balanced design. Such a design ensures minimal interference between different components in order to fully maintain all details and large dynamic swings in music for unmatched sound quality.

Fully Differential, Fully Balanced Design

The PCB of the K9 Pro ESS uses a partitioned layout, wherein not only the power supply and signals are separated, but the analog signal loop is also put in an independent section, guaranteeing the integrity of the audio signal being processed. Every audio signal goes through a mammoth 6-stage circuit to reproduce music as faithfully and as detailed as possible. The six-stage audio circuit reveals every last detail.

Indicator Lights

The RGB indicator lights surrounding the volume knob can light up differently depending on the currently playing sampling rate.

• FiiO K9 Pro ESS Desktop DAC and Amplifier

FiiO K9 Pro ESS Desktop DAC and Amplifier

• Form factor: Tabletop
• Number of headphone channels: 3-Channel
• Recommended headphone impedance: 16 to 600 ohms
• Headphone output power:
• 1/4 inch unbalanced: ≥ 1.1 W into 16 ohms (1% THD)
• 1/4 inch unbalanced: ≥ 2.1 W into 32 ohms (1% THD)
• 1/4 inch Unbalanced: ≥ 281 mW into 300 Ohms (1% THD)
• 4.4 mm balanced: ≥ 1.1 W into 16 Ohms (1% THD)
• 4.4 mm balanced: ≥ 2.1 W into 32 Ohms (1% THD)
• 4.4 mm balanced: ≥ 1.1 W into 300 Ohms (1% THD)
• XLR balanced: ≥ 1.1 W into 16 Ohms (1% THD)
• XLR balanced: ≥ 2.1 W into 32 Ohms (1% THD)
• XLR balanced: ≥ 1.1 W into 300 Ohms (1% THD)

Digital Chipset

• DAC: 2 x ESS ES9038PRO
• USB: XMOS XUF208
• Bluetooth: Qualcomm QCC5124

Analog Circuitry

• Low-pass filter op-amp: 2 x OPA1612
• Volume IC: 2 x NJU72315
• Power amplifier op-amp: 2 x THX AAA 788+

Connectivity

• Analog audio I/O:
• 1 x 4.4 mm TRRRS balanced stereo line input
• 1 x stereo RCA line input
• 1 x stereo RCA output
• 2 x XLR 3-Pin balanced mono output (1 stereo pair)
• 1 x 4.4 mm TRRRS balanced stereo headphone output
• 1 x 1/4  inch TRS unbalanced headphone output
• 1 x XLR 4-Pin balanced stereo headphone output
• Digital audio I/O:
• 1 x TOSLINK optical S/PDIF input
• 1 x RCA coaxial S/PDIF input
• USB:
• 1 x USB-B 2.0 (Digital Input, Update)
• 1 x USB-C (Digital Input)
• Other I/O: 1 x Coaxial SMA Antenna
• Wireless connectivity: Bluetooth (audio streaming, mobile app)
• Bluetooth: 5.0
• Supported audio codecs: AAC, LDAC, SBC, aptX, aptX Adaptive, aptX HD, aptX LL

Performance

• Frequency response:
• RCA line outputs: 20 Hz to 20 kHz -3 dB
• XLR line outputs: 20 Hz to 50 kHz -1.5 dB
• 1/4 inch headphone outputs: 20 Hz to 50 kHz -1.5 dB
• 4.4 mm balanced headphone outputs: 20 Hz to 50 kHz -3 dB
• XLR balanced headphone outputs: 20 Hz to 50 kHz -3 dB
• Maximum output level:
• RCA line: 2.5 Vrms (10-Kilohm Load, 1 kHz)
• XLR line: 5 Vrms (10-Kilohm Load, 1 kHz)
• 1/4 inch headphone outputs: 26 V p-p
• 4.4 mm balanced headphone outputs: 52 V p-p
• XLR balanced headphone outputs: 52 V p-p
• Impedance: Headphone/balanced headphone outputs: < 1 Ohm (32-Ohm Load)
• THD+N:
• RCA line: < 0.00042% (A-Weighted, 1 kHz, 10-Kilohm Load)
• XLR line: < 0.00025% (A-Weighted, 1 kHz, 10-Kilohm Load)
• 4.4 mm line: < 0.00025% (A-Weighted, 1 kHz, 100-Kilohm Load)
• 1/4 inch headphone: < 0.00033% (A-Weighted, 1 kHz, 32-Ohm Load)
• 4.4 mm balanced headphone: < 0.0003% (A-Weighted, 1 kHz, 32-Ohm Load)
• XLR balanced headphone: < 0.0003% (A-Weighted, 1 kHz, 32-Ohm Load)
• SNR:
• RCA line: ≥ 123 dBA
• XLR line: ≥ 128 dBA
• 4.4 mm line: ≥ 128 dBA
• 1/4 inch headphone: ≥ 129 dBA
• 4.4 mm balanced headphone: ≥ 123 dBA
• XLR balanced headphone: ≥ 123 dBA
• Noise:
• Line outputs: < 1.9 mV (A-Weighted)
• 1/4 inch headphone:
• < 2mV (A-Weighted, Aux In)
• < 3 mV (A-Weighted, USB/SPDIF/BT In)
• 4.4 mm balanced headphone:
• < 3 mV (A-Weighted, Aux In)
• 4.5 mV (A-Weighted, USB/SPDIF/BT In)
• XLR balanced headphone:
• < 3 mV (A-Weighted, Aux In)
• 4.5 mV (A-Weighted, USB/SPDIF/BT In)
• Crosstalk:
• RCA line outputs: ≥ 115 dB (1 kHz, 10-Kilohm Load)
• XLR line outputs: ≥ 125 dB (1 kHz, 10-Kilohm Load)
• 1/4 inch headphone: ≥ 75 dB (1 kHz, 32-Ohm Load)
• 4.4 mm balanced headphone: ≥ 114 dB (1 kHz)
• XLR balanced headphone: ≥ 114 dB (1 kHz)
• Channel balance: 0.5 dB

Digital Audio

• Sample rates:
• USB input:
• Up to 384 kHz (PCM)
• Up to 11.2 MHz (DSD)
• Optical S/PDIF input: Up to 96 kHz (PCM)
• Coaxial S/PDIF input: Up to 192 kHz (PCM)
• Bit depths: Up to 32-Bit (PCM)

Compatibility

• OS compatibility:
• Windows
• macOS
• iOS
• Android

Power

• Power requirements: AC Input
• AC input power: User selectable: 110 to 230 VAC, 50/60 Hz

Physical

• Dimensions: 7.9 x 8.8 x 2.8 inch (200 x 224.5 x 72 mm) (without Feet)
• Weight: 6.1 lb (2.8 kg)