Fiio K11 R2R Review

R2R technology has been growing in both popularity and accessibility. Most recently it was Hifiman dropping the EF500 DAC/amp, which sported an abridged version of the company’s Himalaya R2R chip. But now there is new competition in the affordable R2R market: Fiio. Fiio has long been known to aim for great value to performance in their products. At $169.99, the Fiio K11 R2R looks to provide great sound at an earth-shatteringly low price. But even with the R2R functionality, is the K11 worth the excitement? Let’s find out in this review. 

What’s in the Box:

• K11 R2R unit
• power adapter
• power cable
• USB data cable
• 6.35mm adapter
• quick start guide
• warranty card

Build:

First things first: the K11 R2R, like the base model K11, its non-R2R little brother, has a tiny footprint. It’s bigger than a dongle and I would venture to say that most people will not want to bring it on the go. However, its size and light weight make it transportable, so it could provide some flexibility as a travel option. However, I see this going best right on your desk or nightstand – somewhere a low profile like this one is needed. 

That said, even with its low weight, it feels sturdy and strong. This is thanks to its aluminum housing and thoughtful assembly. Its RGB light logo, LCD screen, and single-knob control button give it a feeling of intentionality. The RGB logo changes colors based on the sample rate, and other important playback information can be found on the screen. 

As far as I/O goes, you get a USB-C input, an optical input, a coaxial input/output, and RCA line outputs. I want to highlight the coaxial output which means that you can use this as a DDC too. 

Some other notable design features include RCA metal pressing for better stability, connection, and durability. The system uses a combination of thermal silicone gel and aluminum alloy to better dissipate heat from the amplifier stage. Finally, the K11 R2R uses phosphor copper metal shielding, helping the device to resist external interference. 

Design:

The FiiO K11 R2R DAC/amp is designed with an innovative True 24-bit R2R DAC architecture, featuring fully differential resistor arrays. This precision enables the DAC to produce an accurate, high-resolution sound signature that stands out with its unique charm. The R2R design, which operates in both Non-Oversampling (NOS) and Oversampling (OS) modes, gives users the flexibility to either maintain the original audio sample rate or upsample it to 384kHz, allowing for nuanced sound customization depending on listening preferences.

The K11 R2R is capable of high sample and bit rates, including PCM 384kHz/24-bit and DSD256. In NOS mode, the K11 R2R preserves the original sound texture for an organic experience, while in OS mode, the DAC upsamples audio for a more refined and detailed output. The K11 R2R also incorporates the NJW1195A electronic volume control chip, a 4-channel resistor ladder system designed to ensure low distortion and noise. This advanced component allows for precise and accurate volume adjustment, enhancing the dynamic range and clarity of audio playback, making it ideal for a wide range of listening scenarios and headphone types.

The K11 R2R provides up to 1300 mW of power into 32 ohms when used in balanced mode, and Fiio says this should drive anything up to 350 ohms. So if you’re using planar magnetic headphones like the Sundara or high impedance dynamic headphones like the HD600, you should be covered. 

Sound Impressions:

Low End:

The K11 R2R is generally a neutral-warm DAC/amp. The R2R chip helps bring out the warmth on this device whereas the original K11 is a bit more detail oriented. With that in mind I found bass to be clear and on time. I definitely liked the timbre provided by the DAC and the overall sense of space, but I do think there’s room for improvement in the amp section.

Specifically, I think dynamics could be a bit stronger with a little more force in the bass. Listening with the Sundara, I got a light and pleasant sound – a solid experience – but I found it to be lacking in some character and attack. Listening with Audeze’s LCD-2, I got a little more sense of this character thanks to the warm nature of those headphones. And credit where credit is due: the K11 R2R scaled quite nicely with those headphones, with the LCD-2’s low end warmth being complemented by the leaner, but still smooth, presentation on the DAC/amp.

Midrange:

The midrange is where the K11 R2R does its best work. Vocals are spacious and detailed with, again, a nice touch of warmth and musicality. But most impressive is the instrument separation. Now don’t get me wrong, this isn’t doing detail like significantly more expensive DAC/amps are capable of. But the separation and resolving capabilities in the midrange are pretty impressive for the price. I wouldn’t say the midrange is pushed forward at all, but its overall warm timbre gives it some color and personality. 

Top End:

The treble response on the K11 R2R is a bit dipped. That keeps things in line with an overall warm sounding device. I didn’t find it to be too recessed, but it’s something to keep in mind if you want to use headphones like the Sennheiser HD650, which is already known to be on the darker side. 

Soundstage:

The K11 R2R sports a nice and open soundstage. This has to do with the space provided in the midrange as well as the overall architecture of the DAC. I’ll touch on this more in a second, but I think the DAC pushes the amp further than it would be capable of on its own, and the soundstage is certainly a benefactor of that. 

Final Thoughts:

Overall, the K11 R2R makes for a really solid DAC/amp for an entry level user. Specifically, it gives newer audiophiles a chance to try R2R technology. That said, I think the advantages of the K11 R2R come as a DAC more than an amp. Thus, I would say the K11 R2R is best used as a DAC with an external amp. Either way, it’s a solid value/performance product and a good place to look for beginner audiophiles. 

Find more information about the Fiio K11 R2R at Audio46.