FIIO K11 R2R

The K11 is FiiO's most compact and budget friendly all-in-one desktop DAC and headphone amplifier. A device that uses a single CS43198 DAC chip and dual SGM8262 amplifier op-amps for a fully balanced headphone output. So what exactly is the FiiO K11 R2R?



The FiiO K11 R2R is the exact same device as the K11 with one major difference. This is the first DAC ever made by FiiO to use a discrete, fully differential true 24-bit resistor array to do the decoding instead of delta sigma D/A converter.

Technical highlights

The FiiO K11 R2R features a newly developed four-channel fully differential 24-bit R2R resistor array that consists of 48 resistors per channel. A total of 192 high-precision ultra-thin film resistors with 0.1% accuracy and low-temperature drift between the four channels. The use of fully differential architecture results in lower noise with less FFT harmonics in comparison to a typical one.

The amp section of the FiiO K11 R2R is the same as in the K11 with dual OPA1642 op-amps to handle low-pass filtering and dual SGM8262 operational amplifiers to do the headphone amplification. What is not the same is the NJW1195A digital volume chipset for precise volume adjustment with low distortion between the two channels.

The device supports 24bit/384kHz PCM and DSD256 decoding in contrast to the FiiO K11 which supports 32bit/384kHz PCM and native DSD256 decoding.

You can read more about the FiiO K11 R2R here.

https://www.fiio.com/k11r2r



Dual operating NOS and OS modes

The K11 R2R employs dual operating modes. The NOS mode maintains the original sampling rate without any further signal processing while the OS mode oversamples all input signals to 384kHz. As we are going to discover later on, the NOS mode results in a more musical presentation while the OS mode delivers better technicalities and more clarity.

Connectivity

The FiiO K11 R2R has the same digital inputs and analog outputs as the original model. A well equipped device despite its compact size that features USB type-C, coaxial and optical digital inputs, plus RCA line out and two headphone outputs (6.35mm and 4.4mm). The line output can be set as fixed or variable for driving active monitors such as the FiiO SP3. The USB input supports OTG function for connecting to a smartphone while a USB to coaxial output bridge is also available.

Non Audio stuff

The FiiO K11 R2R has the exact same appearance as the K11 and the only way to tell them apart is the “R2R” logo that is engraved in white letters at the top part of the unit. The slim and compact sized chassis (147x133x32.3 mm), that can fit virtually everywhere, is made from CNC machined aluminum and is available in black and silver finishes plus a red one that is exclusive to the R2R model. Build quality and finish are simply exceptional far surpassing what is expected for the category.

Just like the K11, the R2R edition features a high contrast LCD screen that displays useful information and allows easy access to the configuration menu. The top of the chassis integrates a FiiO logo RGB light that will display different colors according to the input sampling rate. The bottom has a silicone anti-slip pad that prevents accidental move of the unit.



Operating the device

The device is operated with the aid of a single multifunction knob that allows the user to adjust the volume, select the desired input and navigate through the configuration menu. The operation is pretty simple and you can master it in a short time without even reading the manual.

Available actions include to select gain level, set the line output as fixed or variable, switch between NOS and OS modes, set LCD brightness and timeout, set RGB light brightness and pulsing status etc. You can switch between LO and PO on the fly by double-pressing the multifunction button. The unit will remember the last volume setting for LO and PO independently so there is no need to readjust the volume every time you switch modes.

If there is something to complain about is that there is no dedicated gain button and you can't switch between NOS and OS on the fly. A remote control and Bluetooth connectivity would be handy features but I guess that I am asking too much for the price.

Accessories

The package includes an external power adapter, a USB data cable and a 6.35mm adapter plus a quick start manual.



Power talk

The maximum power output of the FiiO K11 R2R is 1300mW/32Ω, slightly lower from the 1400mW/32Ω of the original model. Still powerful enough to run a great variety of full sized headphones, like the FiiO FT5, and at the same time silent enough for use with sensitive earphones. The noise floor is somewhat higher than the K11 but this is something that gets noticeable only with very sensitive earphones.

The FiiO K11 R2R features three gain settings each one with its own independent volume curve that is specially configured for use with different loads. So you always have the perfect volume adjustment no matter if you are going to use very sensitive earphones or more demanding over-ear headphones.



Audio stuff

So, what’s all the fuss about this R2R resistor array DAC? Does it make the FiiO K11 R2R to sound different from the original model or is it some kind of marketing trick?

Of course not, the FiiO K11 R2R does have its own unique sound character that is quite different from the original model. People familiar with R2R designs will know that they tend to sound more natural and realistic than most D/S implementations of the same category. An audio engineer must spend great effort to fine tune a D/S DAC in order to make it sound as natural as similar R2R implementations, and even then the latter will always have the edge in emotion or what we call musicality.

The original FiiO K11 is known for its great neutrality, it has an uncolored, crystal clear and transparent audio profile with exceptional fidelity for the category and at the same time it doesn't sound clinical or sterile. The K11 R2R happily sacrifices a tiny amount of fidelity and transparency for a considerably more musical and organic sound presentation.

The most audible difference is the complete absence of digital artificiality especially in the higher frequencies where the original model has the tendency to introduce some digital glare and artifacts. The treble is smoother and mildly forgiving, more relaxed but without lacking in extension and energy. Detail retrieval and resolution are also stellar while the overall technical performance is competitive, however the sound is presented in a different kind of manner where technicalities are pushed back in favor of a more holistic and sentimental approach.

The K11 R2R produces a natural and realistic timbre especially when you are listening to vocalists and the instruments of the symphony orchestra where it is able to recreate a very colorful and varied harmonic palette.

The sound of the K11 R2R reminds more of an analog set-up rather than the typical entry level D/A converter that is usually achromatic without having a character of its own. It is not that the K11 R2R will introduce sound coloration or it is lacking in fidelity but it does have the means to reconstruct the real essence of the music.

This kind of different sonic approach between the K11 and the R2R gets clearly audible in the low-end where the former presents a firmer and more controlled bass with deeper layering and clarity but the R2R version sounds fuller and more visceral with wider dynamic contrasts. The bass of the R2R has more meat around the bones, it is weighty and rounded while it possesses a very natural reverb.

When it comes to music matching, people who listen to electronic or similar stuff might prefer the advanced technicalities of the K11 but others who value musicality and timbre realism are going to love the R2R. Additionally, the K11 is going to pair better with warmer and slower headphones while the R2R can smooth brighter headphones like some HIFIMAN models.

All R2R DACs that I have reviewed so far have the tendency to outperform their D/S siblings when it comes to soundstage dimensions and the FiiO K11 R2R is not an exception despite being an entry level model. The K11 R2R not only surpasses the K11 but it is also much better than most other D/S DACs of the same category. And by writing “better” I mean that it presents a soundstage that is both wider and deeper than most D/S competitors, with far increased holography and deeper immersion into the recording venue. Everything feels more natural and realistic as the K11 R2R excels in time and space communication.



OS and NOS differences

The OS mode adds extra spice, more transparency and clarity to the sound, the presentation is more technical compared to the NOS, so it bridges the gap between the R2R and the OG versions of FiiO's K11. Still the K11 (and similar D/S DACs) has the edge in technicalities and fidelity, it is livelier and more energetic than the R2R. Additionally the OS mode introduces some kind of sharpness to the treble of the FiiO K11 R2R and robs its musicality. Still this is a nice option to have as it adds versatility and allows for better matching with various headphones and music types.

Line vs headphone output

The headphone amplifier of the K11 R2R is somewhat limiting the performance by killing the unique sound characteristics of the DAC which deserves a better amplifier. It is not that you are not going to enjoy its unique sonic features straight out from the headphone output but you must use the line output in order to truly appreciate what the R2R DAC is capable of doing. The embedded amplifier adds a bit of sterility, it doesn't allow the musicality to come forth, it limits the holographic properties of the soundstage and makes the timbre less natural.

I have paired the FiiO K11 R2R with the Schiit Audio Vali 2+ and I was blown away by the combination. For less than $500, this is a headphone system that sounds incredibly musical and organic with amazing timbre realism and tonal accuracy. So, don't hesitate to buy the FiiO K11 R2R as an all-in-one unit but then invest in a high quality external headphone amplifier (or active monitors) to unleash its full potential.



Conclusion

Right now the FiiO K11 R2R is the most cost effective option in the market for those interested in experiencing the immensely analog and organic timbre of an R2R DAC.

The headphone output might be holding the performance a little back but the line output is truly exceptional. I can only think of a couple of D/S DACs (up to a certain price point) that can match the lifelike and effortless sound presentation of the FiiO K11 R2R but they do have some digital glare issues that the latter doesn't have.

Honestly, this is the most analog and natural sounding DAC FiiO has made so far. I think that it is released to check interest and market reaction when it comes to R2R DAC designs. After finishing this review I am confident that it is going to be a huge success and sell like hot cakes, hopefully encouraging FiiO to design a flagship R2R DAC in the near future. Till then the FiiO K11 R2R is the most affordable R2R DAC ever made with a value that is hard to beat.

The review sample was kindly provided free of charge in exchange for an honest review. The price of the FiiO K11 R2R is $169.99 and you can buy it from here.

Technical Specifications

K11 R2R:

DAC: Fully differential true 24-bit R2R resistor arrays

Volume Control Chip: NJW1195A

USB Input Decoding: Up to 384kHz/32bit, DSD256

Coaxial Input Decoding: Up to 192kHz/24bit

Power Output (Single-Ended): Up to 460mW+460mW at 32Ω

Power Output (Balanced): Up to 1300mW+1300mW at 32Ω

Output Impedance: PO <1Ω (32Ω load), BAL <1.5Ω (32Ω load)

Weight: About 420g

Menu Features:

• SAM (Sampling): Over sampling (OS), Non over sampling (NOS)

• UAC: UAC 1.0, UAC 2.0

• LCD-B (Brightness): 1-3 brightness levels

• LCD-T (Screen timeout): 1/2/5/10/30 and 0 which means always on.

• RGB-M (Colors): 0/1/2/3/4/5/6/7/8 (Follow the audio/Red/Blue/Cyan/Purple/Yellow/White/Green/Or cycle all colors.

• RGB-P: Gives the option for the light to pulse or be constant.

• RGB-B (Brightness): 0(Off)/1/2/3/4/5

• IDLE (Smart Idle): On or Off

• UPDATE: Gives the option for a firmware update.

• RESET: Gives the option to factory reset all the settings.

• FW: Shows the firmware version.

Whats in the box:



If you’ve been swimming in the DAC world for a while, you’ll know not all digital-to-analog converters are created equal. Some are like your trusty Toyota sedan—reliable, efficient, but not exactly thrilling. Then there’s the FiiO K11 R2R DAC amplifier, which feels more like slipping into a classic car that’s been restored to perfection. It's not just about getting from A to B; it's about the ride.

The R2R Heart: An Old-School Approach with Modern Charm

At the heart of the K11 is an R2R DAC, using a trusty resistor ladder to convert digital signals into that warm, analog goodness we all crave. It's an older design, but much like vinyl records and retro sneakers, it's making a big comeback. Unlike the more common Delta Sigma DACs, which take their sweet time stepping through voltages, the R2R DAC just goes, "Nah, I got this," and hits the right voltage immediately. The result? A cleaner, quieter background between notes that feels almost like a deep breath between sips of good single origin coffee.

When I ran it through some of my favorite tracks, the difference was undeniable. Those quiet pauses? Dead silent. Like, ‘I-can-hear-the-neighbors-watching-TV’ level silent. The only time I noticed any noise was with super-sensitive IEMs, but even then, it was more like a faint whisper at the back of a concert hall—nothing that ruined the experience.




Sound Profile: Warmth, Detail, and That Cozy Blanket Feeling

The moment I hit play, the K11 greeted me like an old friend—warm, inviting, and with just enough detail to keep things interesting. The bass is full-bodied but never overbearing. There’s punch and impact, but it knows when to take a step back and let the mids and highs shine.

Now, the midrange is where the magic really happens. It’s the type of sound that makes vocals and acoustic instruments feel intimate and alive. Whether I was listening to some smooth jazz or a folksy singer-songwriter, the K11 kept everything distinct and free of clutter.

As for the highs, if you’re someone who finds sharp treble to be the equivalent of nails on a chalkboard, the K11 is going to feel like a cozy blanket. It’s detailed, but in a smooth, buttery way that makes long listening sessions a breeze. No ear fatigue here—just pure, laid-back enjoyment.

NOS vs. OS Modes: Two Flavors, No Wrong Answer

The K11 comes with a cool feature that lets you toggle between Non-Over-Sampling (NOS) and Over-Sampling (OS) modes, and it's a bit like choosing between a hot cup of tea or a strong espresso and if you know me i am an espresso guy In NOS mode, the K11 leans even further into that warm, analog-like sound. It’s laid-back, smooth, and perfect for when you just want to unwind after a long day. Think of it as a Sunday drive down a scenic road.

Switch it to OS mode, and things get sharper, more focused. The sound tightens up, bringing more clarity to the mids and highs. It’s like flipping on a high-beam—everything just becomes a little more vivid. Personally, OS mode was my go-to for most of my testing. It gave me that perfect balance of warmth and detail without veering too far in either direction.



Power Play: Handling Everything from IEMs to Hungry Headphones

Now, let’s talk power. One of the K11’s strong suits is its versatility. With three gain settings—low, medium, and high—you can easily adjust the output to suit whatever you're plugging in.

Low gain works well with sensitive IEMs, though I did notice a touch of distortion on some lower impedance models (likely due to the higher output impedance). It’s not enough to send you running for the hills, but worth mentioning.

Medium gain hits the sweet spot for most moderately demanding headphones, giving them enough juice to perform beautifully without pushing too hard.

Then there’s high gain. This is where the K11 flexes its muscles. Even with power-hungry headphones like my HiFiMan cans, the K11 performed flawlessly, barely breaking a sweat at mid volume. The dynamics were punchy, the headroom was expansive, and the sound had an authority that made everything feel effortlessly rich.




Pairing my Xduoo MH-02 with the FIIO K11 R2R.

Pairing the Xduoo MH-02 tube amp with the FiiO K11 R2R DAC amp creates an intriguing fusion of analog warmth and digital precision. Both devices bring distinct characteristics to the table, and when combined, they produce a sound signature that blends the best of both worlds.

As someone who enjoys experimenting with different audio gear pairings, the Xduoo MH-02 tube amp and FiiO K11 R2R DAC combo immediately piqued my interest. The K11's R2R DAC offers a natural and detailed sound with its resistor ladder architecture, while the Xduoo MH-02 tube amp adds a distinct analog warmth that is difficult to replicate with solid-state amplification.

When I first connected the K11 to the MH-02, I was curious to see how the pairing would affect the overall tonal balance. The K11 on its own already has a slightly warmer, more organic sound compared to typical Delta-Sigma DACs, and I wondered if the tube amp might overdo the warmth or cloud the details. However, I was pleasantly surprised by how complementary they were.



Sound Signature:

The most noticeable change when adding the Xduoo MH-02 tube amp to the chain is a fuller, more rounded presentation, particularly in the midrange. The K11 R2R DAC already has great resolution and separation, but with the MH-02, there’s a smoother, almost liquid-like quality to the mids and highs. Vocals, in particular, benefit from this pairing—there’s a richness and texture to voices that feels incredibly lifelike. It’s as if the sound opens up, giving more room for instruments and vocals to breathe.

The low end also gets a touch more body with the MH-02. The K11's bass, which is tight and controlled, gains a subtle bloom and warmth without becoming overly bloated. Bass guitars and drums sound deeper and more immersive, adding a bit more weight to the overall presentation. However, the pairing maintains excellent bass control—there’s no sense of sloppiness or excessive bleed into the mids.

What’s especially impressive is that the MH-02 doesn’t sacrifice the K11’s detail retrieval. Tube amps can sometimes introduce too much softness or blur finer details, but the MH-02 strikes a great balance here. The K11’s analytical side still shines through, offering plenty of micro-details and texture in the treble. Instruments like violins, cymbals, and pianos maintain their clarity, but with an added layer of richness from the tubes.

Dynamics and Soundstage:

One of the standout characteristics of this pairing is the enhanced sense of dynamics. The K11 is already good at delivering dynamic swings, but the MH-02 seems to add a touch more punch and energy, especially during crescendos or more complex passages. It brings a sense of musicality to the K11’s analytical precision, making for a more engaging and lively listening experience.

The soundstage also benefits from this pairing. With just the K11, the soundstage is well-defined but not overly expansive. Once the MH-02 comes into play, the soundstage feels more three-dimensional. Instruments and vocals have a greater sense of depth, and there’s more air between them. The result is a more immersive, enveloping soundstage that makes you feel like you’re in the room with the performers.

Build and Usability:

In terms of usability, this setup is relatively straightforward. Both the Xduoo MH-02 and FiiO K11 are compact, desktop-friendly devices, and they complement each other well in terms of design. The K11’s LCD screen is a nice touch, offering quick access to various settings, while the MH-02’s tube glow adds a visual warmth that complements its sonic character.

The MH-02 has ample power to drive most headphones, and when paired with the K11’s flexible gain settings, it’s easy to find the right balance for both sensitive IEMs and power-hungry over-ears. Whether you're switching between high-gain for a planar headphone or low-gain for delicate in-ears, the combination feels versatile and well-rounded.



Final Thoughts on my special combo meal:

Pairing the Xduoo MH-02 tube amp with the FiiO K11 R2R DAC amp creates a sonic experience that feels warm, immersive, and highly detailed. The K11’s R2R DAC brings an incredible sense of precision and detail, while the MH-02 adds that coveted tube warmth without sacrificing clarity or dynamics.

This combination works especially well for listeners who crave a more analog-like sound without losing the technical precision of digital audio. Whether you’re listening to jazz, classical, or acoustic tracks, the pairing brings out the best in both devices, creating a sound that feels both engaging and musical.

If you’re looking to enhance the natural warmth and organic detail of the FiiO K11, adding the Xduoo MH-02 tube amp into the mix is a fantastic way to take your listening experience to the next level.



FiiO K11 R2R—A Warm Hug for Your Ears

The FiiO K11 R2R DAC amplifier is like that friend who always knows how to keep things cozy and laid-back, but still manages to impress you with their hidden depth. Its warm and natural sound is a refreshing change of pace from the overly clinical, precise world of Delta-Sigma DACs. Sure, it may not be the last word in razor-sharp detail or surgical precision, but that’s not the point—it’s here to make music feel human again.

With its rich, textured presentation, the K11 delivers a listening experience that’s as inviting as your favorite comfy chair. Whether you’re in it for a late-night jazz session or just unwinding with your favorite playlist, the K11 has your back, ensuring those long listening sessions stay fatigue-free. It’s not just about hearing your music; it’s about feeling it—and the K11 excels at that.

Is it perfect? Maybe not for those chasing the most analytical sound out there. But for anyone who values warmth, musicality, and a touch of old-school charm, the FiiO K11 R2R is a little slice of analog heaven in our digital world. And honestly, who couldn’t use a bit of that?

FIIO K11 R2R link : https://www.fiio.com/k11r2r

Disclaimer​

Ok, so todays reviewed FiiO K11 R2R was sent to me by FiiO for this review. This fact will not change my thoughts and opinions in this review, and every expression here is entirely my own! I've done my best to provide an honest review based on my experience with the product. My goal is to give you an accurate idea of what to expect if you decide to purchase the K11 R2R.
Furthermore, I really want to thank FiiO for providing me with this review unit and to thank you, the reader, for trusting in me and taking your time to read this review.

Introduction​

I recently got my hands on the FiiO K11 R2R, which is one of the most affordable integrated R2R DAC and headphone amplifiers you can find right now. At $159.99, it’s pretty exciting to see a device with this kind of technology. The K11 R2R stands out because it uses an R2R (Resistor Ladder) DAC (Its trickier to make correctly, but if done right, it should be something special...), unlike the more common Delta Sigma DACs in most modern gear. I've been curious to see how this would impact the sound and if it really brings that organic and natural sound signature that R2R DACs are known for...? Let's see what this little device has to offer...

Unboxing​

When I saw the FiiO K11 R2R package I immediately noticed that it was pretty basic and straightforward... The box had an image of the K11 R2R on the front with its name on it, and the box included exactly the accessories I had expected:

• the K11 R2R unit itself
• a USB data cable
• a power cable
• a power adapter
• a 6.35mm to 3.5mm headphone adapter
• and a quick start guide with a warranty card.

So the overall presentation was basic, but it included everything I need to get it going, which I think is great when considering the asking price!

Technical Specifications and Design​

Design:​

The design of the FiiO K11 R2R is really sleek and I like it a lot! It has a solid aluminum alloy body that makes it look and feel very durable and quality made. The unit I have is the black version and it gives me a clean vibe.
The front panel is simple but functional, with a large volume knob that doubles as a multifunction button. There’s also a 4.4mm balanced output and a 6.35mm single-ended output on the front, which is great for different types of headphones.
On the top of the unit is a big FiiO logo which lights up and you can even change the color, brightness and even the mode in which it lights up to whatever you want.
On the back panel you will find all the inputs and outputs, which includes; a USB Type-C, optical, coaxial, and RCA line-out, so it’s easy to connect to different devices. The whole thing is compact and fits perfectly on my desk without taking up too much space. Plus, it has a HUGE rubber pad on the bottom, so it stays in its place and wont move anywhere by itself!

About the R2R:​

The FiiO K11 R2R uses an R2R DAC, which is a different kind of digital to analog converter that relies on a resistor ladder to produce sound. What’s cool about R2R is that it can instantly hit the right voltage, unlike Sigma Delta DACs, which take small steps to get there whether it's higher or lower and even when staying at the same voltage. Those differences make it very audible! I really noticed that with this R2R DAC, I can hear that it is very quiet between notes.

Delta Sigma on the other side makes some audible hiss or buzz when music is playing, even if the DAC has no background noise and great specifications, but when something is playing, I can hear it; it is very noticeable when I am doing A-B tests. But it is important to remember that in general R2R DACs are not cheap... and that's because the tricky part with R2R is that if it’s not implemented well, it can introduce much more noise, especially with sensitive IEMs...

I actually did notice some of that noise when using the K11 R2R, but when I switched Tidal to exclusive mode, the noise was almost gone, making it much less of an issue. It’s really only noticeable when the sound is coming straight from the operating system. It's hard to exactly explain how the R2R sounds is, compared to the common Delta Sigma, But there are differences and you will have to try it to understand!

Gain Levels:​

The K11 R2R has three gain levels: low, medium, and high. This gives you the option for a more precise power control whenever you are using sensitive IEMs or more power hungry over ear headphones.

Low Gain: This one is good for IEMs or low impedance headphones, however the output impedance is pretty high... approximately 1.5 ohms for the balanced output and 1 ohm for the SE one. this makes low impedance IEM a bit challenging for this AMP to drive properly without distortion...

Medium Gain: A good middle ground, perfect for most headphones that don’t need extreme power but still benefit from a bit of extra push.

High Gain: This is where the K11 R2R shines for power hungry headphones. It delivers maximum output and is best suited for high impedance or less sensitive headphones. This one could drive my HE4XX and K712 Pro on 30%-40% volume, which is very good!

More settings:​

• SAM (Sampling): Over sampling (OS), Non over sampling (NOS)
• UAC: UAC 1.0, UAC 2.0
• LCD-B (Brightness): 1-3 brightness levels
• LCD-T (Screen timeout): 1/2/5/10/30 and 0 which means always on.
• RGB-M (Colors): 0/1/2/3/4/5/6/7/8 (Follow the audio/Red/Blue/Cyan/Purple/Yellow/White/Green/Or cycle all colors.
• RGB-P: Gives the option for the light to pulse or be constant.
• RGB-B (Brightness): 0(Off)/1/2/3/4/5
• IDLE (Smart Idle): On or Off
• UPDATE: Gives the option for a firmware update.
• RESET: Gives the option to factory reset all the settings.
• FW: Shows the firmware version.

Additionally, a very long press (I think about 5 seconds) turns the K11 R2R completely off, and to turn it back on, just press on the knob.

Specs:​

• Colors: Black, Silver, Red (planned for later production)
• Main control chip (single-chip microcomputer): GD32F303RET6
• DAC: Fully differential true 24bit R2R resistor arrays
• Volume control chip: NJW1195A
• USB input decoding: 384kHz/32bit, DSD256
• Coaxial input decoding: 192kHz/24bit
• Optical input decoding: 96kHz/24bit
• USB connector: Type-C
• Display: Custom LCD screen
• Dimensions: 147x133x32.3mm (including feet)
• Weight: About 420g
• Power supply: DC12V 2A external adapter
• SE power output 1: L+R≥460mW +460mW (32Ω, THD+N＜1%) (32Ω/single-ended/high gain)
• SE power output 2: L+R≥50mW+50mW (300Ω, THD+N＜1%) (300Ω/Single-ended/High gain)
• BAL power output 1: L+R≥1300mW+1300mW (32Ω, THD+N＜1%) (32Ω/Balanced/High gain)
• BAL power output 2: L+R≥220mW+220mW (300Ω, THD+N＜1%) (300Ω/Balanced/High gain)
• Frequency response: 20Hz~50kHz: attenuation＜1.3dB
• SNR: ≥115dB (A-weighted)
• Noise floor: PO＜7.2uV (A-weighted); BAL＜14.1uV (A-weighted)
• Output impedance: PO＜1Ω (32Ω load); BAL＜1.5Ω (32Ω load)
• THD+N: LO＜0.02% (1kHz/10kΩ)

Sound performance​

When it comes to sound, the FiiO K11 R2R has a really unique character that stands out from other DACs I've used. The first thing I noticed was its warm and natural tone. The bass has a nice punch to it, yet without overpowering the rest of the sound. And I will add more... Despite the warmer tone the sound is very detailed! It’s not as detailed as some other DACs, but its details make through in another way, which is different from a regular Delta Sigma DAC...

As I said, the sound of this r2r, at least the way it goes through the amplifier there... sounds warmer yet still "analytical" (not in the term of high frequencies, but rather the way each note is delivered...), as if there is less smoothing. Things sound sharper, and not necessarily in terms of high frequencies...

I can describe it as having the feeling that between notes there is silence compared to other Delta sigma DACs I have.

You can imagine this in way that the R2R can reach each frequency almost instantly compared to the steps of voltage in Delta Sigma.

Now the mid range of the K11 R2R, which adds a bit of warmth, especially to vocals and instruments like guitars and pianos. Vocals come through with a smooth quality, which is nice for genres like jazz or acoustic music. Yet even in more complex tracks, the mids are never muffled and stuffed together because of this R2R characteristic! like the different elements have their own moments in the track and each sounds very detailed without any smoothening and noise between notes.

The treble is where the K11 R2R shows its softer side. It doesn’t have that sharp, sometimes harsh edge that can make listening fatiguing. Instead, the high notes are smooth and easy on the ears which makes it great for long listening sessions. The best part is, that it doesn't lose too much detail, even though its sound signature is warmer.

NOS and OS modes:​

One of the interesting features is the ability to switch between No Over Sampling (NOS) and Over Sampling (OS) modes. In NOS mode, the sound is even warmer and more relaxed, almost like listening to vinyl. It’s great if you want a really smooth and organic sound, almost (but definitely not) tube like. On the other hand, the OS mode tightens things up a bit, adding more detail and clarity, especially in the mids and highs. I found myself using the OS mode more often because it strikes a good balance between warmth and detail.

Overall, the K11 R2R offers a sound that’s more about enjoying the music! It’s a bit like sitting back and letting the music wash over you. And even if you want to hear details, you don't need to struggle with analyzing the sound, you can still lay down and enjoy the details.

Conclusion​

So after spending some time with the FiiO K11 R2R, I can easily say that it’s a solid choice for anyone looking to step into the world of R2R DACs without breaking the bank!

The warm and natural sound, yet still detailed (in its own way...) sound is its standout feature which makes it a pleasure to listen to, especially if you are into a more laid back and organic sound. And the ability to switch between NOS and OS modes adds some versatility, which is great for when I'm having a different listening vibe.

However, it's not without its quirks. The K11 R2R isn’t as powerful (although I had enough power for any of my harder to drive headphones... but some people may find it lacking...) or as technical as some of its competitors. There's also a noticeable background noise issue with sensitive IEMs, but it’s mostly manageable if you’re using exclusive mode.

In the end, the K11 R2R offers a unique and enjoyable sound that stands out from the common Delta Sigma DACs. So If you value a natural and analog like sound over absolute technicalities, the K11 R2R is definitely worth considering, especially when taking into a count its price point! And I really think that it is a great entry into the world of R2R which offers a sound that’s both engaging and easy to live with for long listening sessions.