FiiO k11 R2R DAC Headphone Amplifier Review

The FiiO K11 R2R is one of the best value options for those looking to enjoy the more natural analog sound of an R2R DAC and to experience the smoother, more natural character of an R2R DAC. The K11 might not be as strong or versatile as the original, but its natural sound and good performance make it a great option.

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It reimagines the award-winning FiiO K11, a DAC and headphone amp that earned the 2023 Best Desktop DAC/Amp title, by swapping out the Cirrus Logic delta-sigma chip for a rare resistor ladder (R2R) DAC. I tested the K11 R2R in various setups to assess its performance and see whether an affordable R2R option can make a real difference at this level.

Features

The most defining feature of the K11 R2R is its internal R2R DAC, a design that uses a series of precision resistors to convert digital signals to analog, rather than the more common delta-sigma approach. Though this older method is generally seen as lower in measured accuracy, it’s valued by many listeners for its warm, analog-like sound. FiiO’s implementation includes a dual ladder setup, with 2×48 matched thin-film resistors per channel, totaling 192 resistors, capable of decoding PCM up to 384kHz/24-bit and DSD256.

FiiO also included two playback modes — NOS (No Oversampling) and OS (Oversampling). NOS mode preserves the original sample rate and delivers a smoother, more relaxed sound, while OS mode upsamples the signal to 384kHz, providing a sharper, more technically refined presentation. Output power remains solid, with up to 1300mW at 32 ohms from the balanced output and 400mW from the single-ended output. While that’s slightly less than the original K11, the performance is still strong for this price range. With three gain stages included, the K11 R2R is well-suited for everything from sensitive IEMs to demanding over-ear headphones.

Design And Build Quality

The K11 R2R keeps the minimalist and functional design of the original K11. Its body is crafted from anodized aluminum alloy, giving it a modern, matte finish that complements desktop setups, especially those with Apple hardware. It’s available in black and silver, with a red edition coming soon. The front panel features a multi-function volume knob, flanked by a 4.4mm balanced output and a 6.35mm unbalanced output. A VA LED display shows playback info and volume levels.

Around the back, the K11 R2R provides a USB Type-C input, coaxial and optical inputs, and RCA outputs for speaker or amp connection. It measures 147mm x 32mm x 133mm and weighs just 420 grams, making it compact and desk-friendly. The top of the unit features an illuminated FiiO logo, which can glow in eight colors and five brightness levels or be turned off completely. A rubber pad runs the full length of the base to prevent sliding.

Connectivity and Inputs/Outputs

The K11 R2R offers all the essential connectivity features. The rear panel houses a USB-C input supporting PCM 384kHz/32-bit and DSD256, and it’s plug-and-play with Windows 10 or newer and macOS. Connecting it to my PC was seamless, though my iPhone 14 didn’t detect the device using Apple’s Lightning to USB-C cable, which may require a powered adapter.

Also on the rear are coaxial and optical inputs for use with streamers, CD players, and more. The coaxial input can double as an output, letting users send digital audio to an external DAC if needed. RCA outputs allow for connection to powered speakers or external amps. On the front, you’ll find the two headphone outputs: a balanced 4.4mm and an unbalanced 6.35mm offering different power and noise characteristics.

Controls

Controlling the K11 R2R is easy, thanks to the smart use of the volume knob. A short press brings up the input selection menu (USB, coaxial, optical), a double press switches between output modes (headphone, pre-out, line-out), and a long press opens the main menu.

One of its best features is a separate volume memory for the headphone and line-out. The pre-out volume is now adjustable, unlike on the original K11. The VA LED screen is crisp and readable in both bright and dim conditions, and screen brightness can be adjusted. You can also set it to turn off automatically after a set time. Menu options include gain control, NOS/OS switching, screen settings, and power behavior.

Sound Impressions

For testing, I used the Sennheiser HD 580 Precision and Moondrop Blessing 3 IEMs. Overall, the K11 R2R presents a warm, laid-back sound that leans toward musical enjoyment over clinical detail. Bass is punchy and satisfying, though it lacks the texture and impact of more neutral, high-output amps like the Topping L30 II. That said, mid-bass is thick and full, adding depth and weight to synths and bass guitars.

The midrange is smooth and emotional, especially on vocals, which sound closer and more intimate. However, the tradeoff is some loss of clarity and resolution in busy passages. String instruments and pianos can sound slightly compressed or lacking in separation when the mix becomes more complex.

Treble is relaxed and non-fatiguing, especially with better-mastered recordings. On simpler tracks, cymbals and bells sound pleasant. But in more congested or poorly mastered songs, the treble becomes blurry and can even sound harsh or messy, sometimes leading to listening fatigue. The K11 R2R is not an ideal choice for treble-focused or detail-heavy music.

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Imaging and soundstage are serviceable in OS mode. Bass instruments have good dynamics, but higher-frequency elements don’t pop as much. While not class-leading, the overall stage is wide enough to create a pleasing experience, with vocals up front and deep bass extending around the listener.

NOS vs OS Mode

The two sampling modes produce noticeably different results. NOS mode sticks to the original sampling rate and gives the sound a warm, tube-like feel. It’s soft, organic, and perfect for long, relaxed listening sessions. However, resolution, particularly in the mids and highs, takes a hit, and more complex tracks can feel smeared.

OS mode, on the other hand, oversamples everything to 384kHz and brings better clarity, micro-detail, and treble separation. Instruments have more air and definition, and while it still leans warm, the overall experience is more complete and technically satisfying. In day-to-day use, I found OS mode to be the better choice, offering fewer tradeoffs without losing the pleasant tonal character of the R2R DAC.

Conclusion

The FiiO K11 R2R is a welcome surprise in the world of affordable DAC/amps. At under $170, it offers a rare taste of R2R sound, something usually reserved for high-end gear. It may not match delta-sigma DACs in raw performance or transparency, but its warmth, musicality, and emotional delivery set it apart.

The build is excellent, the feature set is generous, and the inclusion of both NOS and OS modes gives users more flexibility than ever. The slightly reduced power compared to the original K11 is a fair trade-off for the analog character the R2R brings.

For those curious about R2R but not ready to invest hundreds or thousands, the K11 R2R is a highly recommended starting point and possibly a long-term companion for laid-back, immersive music enjoyment.

FiiO K11 R2R Specifications

DAC Type:

• R2R (Resistor Ladder) DAC
• Dual Ladder Array with 2×48 matched thin-film resistors per channel (192 total)

Supported Audio Formats:

• PCM: Up to 384kHz / 24-bit (USB)
• DSD: Up to DSD256 (USB)
• Optical/Coaxial: Up to PCM 192kHz / 24-bit

Sampling Modes:

• NOS (No Oversampling)
• OS (Oversampling to 384kHz)

Headphone Output Power:

• Balanced 4.4mm: Up to 1300mW + 1300mW @ 32Ω
• Single-Ended 6.35mm: Up to 400mW + 400mW @ 32Ω

Output Impedance:

• Balanced: <1Ω
• Single-Ended: <1Ω

Gain Levels:

• 3 Gain Stages: Low, Medium, High
• Independent volume curve per gain level

Volume Control:

• NJW1195A 4-channel electronic volume controller
• Low-distortion, low-noise ladder-based potentiometer

Inputs:

• USB Type-C
• Optical (TOSLINK)
• Coaxial (shared In/Out)

Outputs:

• 4.4mm Balanced Headphone Output
• 6.35mm Single-Ended Headphone Output
• RCA Line-Out (Pre-out or Fixed Line-Out selectable)

Power Supply:

• 17 x Low-Noise LDO Regulators
• 2 x DC-DC Converters
• External 12V DC Switching Power Supply
• Internal voltages: −9V, +8V, ±7.5V, ±6V, 5.4V, 3.3V, 1.8V, 1.2V

Capacitors:

• Beryl Solid Capacitors (Low ESR)

Display:

• VA LED screen (adjustable brightness)
• Displays volume level, sample rate, input source, and more

Lighting:

• RGB FiiO Logo with 5 brightness levels and 8 color options
• Can be turned off

Body Material:

• CNC-machined Aluminum Alloy
• Anodized finish

Dimensions:

• 147mm (W) × 32mm (H) × 133mm (D)
• Weight: 420g

System Compatibility:

• Windows 10/11 (driverless)
• macOS
• Android (OTG)
• iOS (via compatible adapters)