The FiiO K11 R2R is a desktop DAC and headphone amplifier designed for enthusiasts seeking natural, precise, and technically refined sound reproduction. At the heart of the design is a true, fully differential 24-bit R2R DAC, crafted with high-precision resistor arrays, a choice that prioritizes musicality, tonal coherence, and micro-detail over traditional delta-sigma solutions. The K11 R2R supports both NOS (Non-OverSampling) mode, for a more organic and analog sound, and OS (OverSampling) mode, ideal for those seeking greater control and definition.
The headphone amplifier section is equally refined, with a high output power of up to 1300 mW + 1300 mW, capable of driving both dynamic and planar headphones with authority. Volume control is handled by the high-quality NJW1195A electronics, which ensures precise adjustments, low noise, and perfect coherence between channels. Three gain levels and three volume curves are also available, allowing you to tailor the device's behavior to any type of headphone and listening preference.
The K11 R2R uses a custom-designed audio circuit and power supply, with carefully selected components such as high-quality beryllium solid capacitors, designed to ensure signal stability, dynamics, and clarity. Completing the package is a custom LCD display that clearly provides all operating information, flanked by the distinctive FiiO logo with RGB lighting, adding a modern and elegant touch to your desktop setup.
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True 24-bit Fully Differential R2R DAC
The FiiO K11 R2R uses a truly fully differential 24-bit R2R DAC, developed in-house by FiiO. The structure employs four independent channels, with two high-precision thin-film resistor arrays for each channel, for a total of 192 resistors selected with 0.1% tolerance and an extremely low thermal drift of just 30 ppm. This architecture ensures extremely accurate digital signal conversion, delivering natural, nuanced sound with a distinctive timbre typical of the best R2R implementations.
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Comparison between fully differential and traditional architecture
The FiiO K11 R2R adopts a fully differential architecture, an advanced solution that achieves significantly lower noise levels than traditional architectures. This approach effectively reduces unwanted harmonics in the FFT analysis, delivering a darker, cleaner soundstage, with greater perception of musical detail and improved instrument separation.
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FFT Analysis – Fully Differential Architecture
The FFT analysis of the fully differential architecture shows:
• Reduced noise floor
• Fewer spurious harmonics
• More linear and faithful signal
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FFT Analysis – Traditional Architecture
In comparison, the FFT analysis of a typical architecture shows:
• Higher noise floor
• Increased harmonics
• Lower overall signal clarity
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Dual NOS and OS Playback Modes
The K11 R2R offers two selectable operating modes to suit different listening preferences. NOS (Non-Oversampling) mode maintains the original sampling rate of the audio file, preserving the signal structure and offering a more organic, direct, and engaging sound. OS (Oversampling) mode, on the other hand, performs global upsampling up to 384 kHz, improving signal linearity and accuracy for more detailed, cleaner, and controlled playback.
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True 24-bit decoding and high-resolution audio support
With support for PCM signals up to 384 kHz/24-bit and DSD256, the FiiO K11 R2R can effortlessly handle high-resolution audio files, revealing every minute detail in the recording. The result is excellent sound reproduction, with great depth, dynamics, and precision. DSD256 playback requires the DSD output to be set to Native mode on the source device, with internal conversion to PCM before decoding via the R2R arrays.
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High-quality NJW1195A electronic volume control
Volume control is handled by the NJW1195A chip, a 4-channel electronic controller based on a resistor network. This solution ensures extremely low distortion, low noise, and excellent coherence between channels, allowing extremely precise adjustments and maintaining intact signal quality even at low listening levels.
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Three Gain Levels and Three Independent Volume Curves
The K11 R2R features three gain levels and three selectable volume curves, designed to perfectly match any type of headphone. Whether using high-sensitivity IEMs or more difficult-to-drive over-ear headphones, the system delivers optimal volume control, improved dynamics, and a balanced listening experience.
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Custom-Designed Audio Circuit
The digital audio signal is transmitted via a USB interface processor to a digital audio bridge. After processing by an FPGA, the signal is sent to the R2R DAC, which decode it for a 4-channel output.
The signal then passes through two TI OPA1642 op-amps, which perform the low-pass filter and single-ended analog signal conversion. Volume control is handled by the NJW1195A electronic chip, which allows for extremely precise and balanced adjustment.
The output stage uses two SGM8262 op amps, responsible for 4-way phase inversion and final amplification, enabling both single-ended and balanced analog outputs.
The audio circuitry also integrates gain controls, a dedicated headphone protection circuit, and a pop noise suppression system, ensuring high sound quality, reliability, and operational safety.
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Dedicated High-Purity Power Supply
The K11 R2R features a custom-designed power supply system, based on 17 ultra-low-noise LDO voltage regulators and two DC-DC converters, capable of providing dedicated multi-channel power supplies for:
9V, 8V, ±7.5V, ±6V, 5.4V, 3.3V, 1.8V, and 1.2V.
This complex system is combined with a custom external 12V switching power supply, designed to ensure maximum power purity, reduce interference, and create a solid foundation for stable and high-performance power delivery.
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High-Quality Beryllium Solid Capacitors
The use of beryllium solid capacitors, featuring ultra-low ESR and high interference suppression capability, ensures a stable and clean power supply. This significantly contributes to more transparent, dynamic, and artifact-free sound reproduction.
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High-Power Output for Demanding Headphones
With a 32-ohm load, the FiiO K11 R2R can deliver up to 1300 mW + 1300 mW in balanced mode, enough power to drive a wide range of Hi-Fi headphones with authority. This power reserve allows you to fully exploit the headphones' potential, ensuring control, dynamics, and maximum definition.
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High-Readability LCD Display
The device features a custom, high-contrast LCD display designed for continuous use without the risk of burn-in. The display provides essential information such as sampling rate, volume level, gain, and output mode at a glance, enhancing your everyday listening experience.
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Multifunction Knob for Total Control
The K11 R2R's front knob is the device's control center: it allows you to power it on and off, navigate menus, adjust the volume, and provide quick access to key functions. By combining presses and rotations, you can perform complex operations intuitively, including quickly switching between PO, PRE (LO SE) and LO modes with a double press.
Metal-Pressed RCA Connections
Metal-pressed RCA connectors ensure a solid and stable connection, reducing the risk of loose contacts and improving long-term durability. The reinforced structure helps maintain a clean and reliable audio signal, ideal for hi-fi systems and high-end desktop setups.
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Optimized Thermal Dissipation System for the Headphone Amplifier
The headphone amplifier's cooling system has been enhanced with a combination of silicone thermal gel and an aluminum alloy chassis. This solution ensures rapid heat dissipation, improving operational stability and preserving audio performance even under heavy loads.
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Phosphor Copper Shielding with Protective Coating
The phosphor copper shielding shell is passivated for resistance to corrosion and oxidation. This advanced shielding effectively reduces external electromagnetic interference, ensuring audio signal processing with high precision and fidelity.
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DC Protection for Maximum Headphone Safety
The DC Protection system prevents any abnormal DC output from reaching the headphones, preventing damage to the drivers.
This feature ensures safe and reliable use, offering complete peace of mind even during extended listening sessions or setup changes.
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Smart Power Saving
The Smart Power Saving function automatically detects the absence of an audio signal and, after a period of inactivity, switches the device to a low-power mode.
In addition to reducing power consumption, this system helps limit overheating, preserving the longevity of internal components. When audio signal resumes, the FiiO K11 R2R automatically returns to normal operating mode, without any manual intervention.
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Package Contents
K11 R2R x 1
Power adapter x 1
Power cord x 1
USB data cable x 1
Headphone adapter x 1
Quick Start Guide x 1
Warranty card x 1
