Measurements and Review: FiiO K11 & K11 R2R – How Much Does a DAC Really Matter?

Hello folks, how’s it going? Here’s the comparison many of you have been asking for over the past couple of months. Today we’re comparing two desktop DACs from FiiO—actually the same K11 model, but with one key difference: the DAC chip inside them. While the standard K11 uses a classic Delta-Sigma solution based on the CS43198, the K11 R2R features FiiO’s first in-house R2R DAC. In the end, is there a real difference between these two products? And more broadly, how much of an audible difference can you detect between two audio sources with different architectures? Let’s see if we can find out.

In the sections below, we’ll first cover the standard K11. Then we’ll have a dedicated section for the K11 R2R. For measurements, we’ll talk about both, comparing them where relevant.

Vídeos & Links

Unboxing (K11 R2R) - https://www.youtube.com/shorts/0xbffgZp5D8

But the K11 on AliExpress - https://s.click.aliexpress.com/e/_oDeGBn3

Buy the K11 R2R on AliExpress - https://s.click.aliexpress.com/e/_oFrkjtB

Overview

In general terms, the FiiO K11 is a desktop DAC with an aluminum chassis, an alphanumeric display, and a multifunction volume knob. It’s presented as an evolution of its predecessors—the K5 Pro, K7, and K9—positioned as an entry-level desktop solution. According to FiiO, its strengths include a variety of inputs and outputs, a claimed maximum output power of 1400mW into 32 ohms, and a sleek design.

The base model retails for around USD 129.99 internationally. To purchase the K11 on AliExpress, use our link!

Build & Connections

The K11 is a CNC-machined aluminum desktop DAC. Its design follows a minimalist trend, with fewer controls and screens, visually resembling Apple products. It looks right at home next to a Mac Mini, iMac, or MacBook. Personally, I’m a fan of this aesthetic and find it better resolved than other FiiO desktop DACs. It’s a shame this is the only product in their lineup with this look.

On the back panel, we find several input and output connections:

• Power input – DC 12V

• USB-C data input

• Optical S/PDIF input (TOSLINK)

• Coaxial S/PDIF input

• RCA line output

On the front panel:

• 6.35mm single-ended headphone out (pictured with a 3.5mm adapter)

• 4.4mm balanced headphone out

• Alphanumeric VFD display

• Multifunction volume knob

On top, there’s a customizable RGB-illuminated FiiO logo. You can configure this illumination via the device itself—details are in the operation section.

Correction: We previously stated the CS43198 lacked the Class-H amplifier found in the CS43131. That’s incorrect—the CS43198 does include an integrated amplifier, even though it’s not shown in its block diagram. We’ve corrected the paragraph below accordingly.

The K11 is based on Cirrus Logic’s CS43198 Delta-Sigma DAC, a sibling of the CS43131 used in many dongles. However, unlike typical implementations, the K11’s amplification stage is handled separately in a dedicated circuit—a logical choice given the promised 1400mW output into 32 ohms. Below is the block diagram from FiiO’s website.

Amplification in the K11 is handled by the SGM8262-2 from SGMicro, a low-noise, high-output-current op-amp. This chip delivers the necessary current (over 200mA) to drive low-impedance headphones, ensuring the power output meets spec.

Unboxing & Accessories

We didn’t unbox the K11 since it was a loan from one of our subscribers. However, we did unbox the K11 R2R, which comes with an identical package—you can check it out in the video above.

The kit is very basic: it includes the DAC, power supply, and a 6.35mm-to-3.5mm adapter. I appreciate the inclusion of the adapter, since most of my headphones use 3.5mm plugs. However, I wish FiiO had simply used a native 3.5mm jack—using an adapter visually clashes with the minimalist aesthetic.

Features, Operation & Use

According to FiiO’s website, the K11 includes:

• 3 gain modes: Low, Medium, High

• 3 different gain curves per mode

• 5 digital reconstruction filters

• Non-Oversampling (NOS) mode listed as Filter 6

• Output selection between front (Phone Out) and rear (Line Out)

• Configurable RGB illumination for the top FiiO logo

All settings are accessible via the front panel by rotating and pressing the volume knob, with prompts displayed on the screen. FiiO provides a video FAQ for guidance.

The volume knob feels tactile both when rotated and pressed, giving a satisfying click. However, volume adjustment isn’t very precise—you’ll need multiple clicks to see the volume level change. It’s functional, but I wouldn’t call it ideal.

One odd omission: the K11 isn’t supported in the FiiO Control app. This is both good and bad. It’s good because it means the device’s interface is fully self-contained—all settings are accessible via onboard controls. But with so many settings, navigating everything through a single knob (rotating, clicking, long-pressing) gets tedious and slows down quick adjustments.

Personally, I like the RGB lighting on the K11. You can tweak colors, effects, and brightness to match your setup’s vibe. Usually, I don’t think minimalist aluminum designs pair well with RGB (often associated with flashy “gamer” aesthetics), but FiiO implemented it elegantly—it stands apart from an Apple clone. And of course, you can turn it off completely if you prefer.

As noted earlier, the K11 lets you choose among five reconstruction filters available on the CS43198. There’s also a sixth mode—NOS (Non-Oversampling)—which disables oversampling and reconstruction filtering. We’ll explore what that does in the measurements section.

K11 R2R

Before we dive in, this article assumes you’re already familiar with R2R DACs and how they differ from Delta-Sigma DACs. We plan to cover that topic in a future post.

With that said, what changes in the K11 R2R? Very little on the outside. Both units share the same chassis, materials, display, knob—you name it. The only external difference is a laser-etched “R2R” marking on the front.

Internally, though, the K11 R2R is quite different. It houses FiiO’s first in-house R2R DAC. Below is FiiO’s implementation, where an FPGA converts incoming formats to PCM and drives the individual bits to the R2R resistor ladder—a common approach across the industry. Here, the FPGA handles the interface and timing, while shift registers (74LVC595) efficiently assign bits to the resistors without wasting valuable FPGA pins, ensuring linearity.

In the standard K11, volume control is handled internally by the CS43198 DAC—a typical feature in modern integrated DACs. This control isn’t inherently present in FiiO’s R2R DAC, so they implemented it using an NJW1195A volume control chip.

When using the K11 R2R, we noticed some differences stemming from this alternative design. The most notable is an extra mode in the Single-Ended output called “LO SE,” enabling volume control over the RCA line out. This lets you use the K11 R2R as a preamp in higher-power setups. The Delta-Sigma model lacks this feature.

Another difference: the R2R implementation offers only two reconstruction modes—Oversampling (likely with a single fixed filter) and Non-Oversampling. Personally, I prefer this simpler approach since I rarely find audible differences between multiple filters.

All this additional hardware increases cost: the K11 R2R retails for $159.99—about $30 more than the base model. To purchase the K11 R2R you can use our link!

Measurements

Let’s jump into measurements for both DACs to objectively compare them. First, the K11 and its six gain modes. As we see, it achieves a maximum output of 1377mW @ 32 ohms in high gain and balanced output.

Now the K11 R2R with the same settings: it maxes out at 1250mW @ 32 ohms—a bit below spec and slightly lower than its Delta-Sigma sibling.

Both models have plenty of power to drive most headphones on the market. Some say the K11 is a desktop DAC “meant for IEMs”—which is wildly exaggerated. With these numbers, it easily powers most over-ear headphones. To double-check, try our headphone power calculator with your headphone specs to see if the K11 or K11 R2R can handle them.

With our Cosmos ADC measurement system, we can also discuss distortion and noise more precisely. Let’s start with the 1kHz tone spectrum on the Single-Ended output into a 33-ohm load. Both DACs were set to high gain and OS filter for optimal signal.

First, the Delta-Sigma K11:

Now the R2R model:

Which brings us to the comparison:

• K11: THD – 0.00023%; THD+N – 0.0015%

• K11 R2R: THD – 0.018%; THD+N – 0.018%

Our setup yielded results close to FiiO’s published specs for the K11, and even slightly better than spec for the K11 R2R. There’s no clear consensus on how much THD is audible—numbers range from 5% down to 0.1%. From my experience, visible waveform distortion on screen typically disappears below 0.1% THD. We’ll use this as our practical benchmark.

By this measure, both units have excellent distortion performance. Now, for curiosity’s sake, let's take a look at the NOS mode spectrum on both unit. First the K11 NOS:

Now the K11 R2R NOS:

In the K11, there’s a clear rise in third harmonic without much impact elsewhere. In the K11 R2R, the spectrum looks noisier overall, making it harder to assess specific changes. There’s a slight rise in noise and unwanted spectral components at higher frequencies, but not enough to affect total distortion metrics.

Next, a multitone test shows how each DAC handles a complex signal. Again, we used a 33-ohm load to stress the output stage. First the base K11:

Now the R2R:

Notice how the R2R has more baseline noise outside the input tones—not ideal for this test. However, the added noise isn’t enough to compromise real-world listening. Both deliver great performance, far exceeding what is required for human hearing.

Now let's do a frequency response graphs, to check how the DAC handles the frequencies. No surprises here as both units performed as expected. Again we start with K11:

Then the K11 R2R:

Performance is nearly identical, with a slight phase difference in the R2R— which is insignificant.

Now a crosstalk test: we sent signal to one side and measured the opposite, across three load conditions—open, 330 ohms, and 33 ohms.

First the K11:

Then the K11 R2R:

We observed higher crosstalk at lower load impedances. I don’t yet have a full explanation for this, but the pattern is consistent across tests. Still, under open-circuit conditions, crosstalk is excellent.

We took additional measurements of the units and will update this post with links once our measurement page is online.

Sound Quality

So, measurement-wise, both deliver solid numbers, with the base K11 slightly more powerful, quieter, and lower in distortion than the R2R. But what about listening impressions?

For testing, I used these headphones:

• Moondrop Aria Snow

• Unique Melody MEST Mk. 2

• Hifiman HE400SE

• Sennheiser HD800

My test playlist is a set of familiar Spotify tracks—not technical test signals, but songs I know well and have used to spot differences between gear.

I’d love to tell you I heard major differences between the two DACs—that the R2R sounded more “natural” and less “analytical” than the Delta-Sigma, or that NOS mode was transformative. But the truth? I couldn’t hear any meaningful difference between them.

Both delivered clean, quality sound at sufficient volume for my headphones. Bass, mids, and treble all sounded as expected. For instance, the sub-bass intro in “String Theory” came through beautifully on both. The layered details in “Chopsticks” were equally present.

If anything, I noticed the base K11 sounded about 1–2 volume steps louder than the R2R at the same knob position (e.g., K11 at 30 vs. R2R at 32 for matched loudness). Whether that’s unit-specific or universal, I can’t say.

As for NOS mode, I found it a complete waste of time. Oversampling and filtering exist to improve signal fidelity. Disabling them effectively adds noise without reliably improving sound quality. It’s there if you want to experiment—but personally, I see no upside.

And this brings us to a broader question: even if there are measurable differences between devices, how much do these differences in DACs truly matter for our listening experience? Personally, I believe the role of source devices has been greatly exaggerated—a combination of an industry that needs to sell products through marketing and reviewers who often lack objective testing methodologies.

At the end of the day, what a consumer really needs is a well-implemented product. If the final destination of that signal is your ears—and not another piece of equipment in a lab—you can be confident that most devices on the market today will perform perfectly well for actual listening. And this is no exception for K11 and K11 R2R. Both are well designed and quality-wise indistinguishable from one another.

In short: I wouldn’t invest heavily in source devices. I’d rather prioritize better speakers and headphones.

Final Thoughts – Which One Should You Buy?

After testing both DACs extensively, I face the tough task of recommending one—or saying it doesn’t matter. They’re very similar products, with a price difference and an expectation of “different” sound from the R2R.

But to me, there’s a clear winner: the standard K11 with Delta-Sigma technology. It’s cheaper, more powerful, and objectively performs better—even if those differences aren’t audible. The K11 R2R is a solid execution of an R2R DAC from FiiO, but it costs more and measures worse. It only makes sense if you truly need the RCA Line Out volume control, or simply want to own an R2R DAC for its own sake—which, I’ll admit, is why I’m keeping mine on my desk as a reference from its category.

See you next time!