Setup, Customization, and Performance

Desktop Setup

Given the FiiO K11 R2R is a DAC/headphone amp/preamp unit, the number of cables that go in the back and front is fully dependent on how you plan on using it. I suspect most readers of this review will be using it primarily as a USB DAC for input, although the other inputs can be quite handy with non-desktop sources, such as a CD player or a phono stage. The smaller form factor and Type-C input also makes it easier to connect this to a mobile device, let alone laptops and desktops, but of course the two-piece power supply prevents this from being a portable solution. It would have been nice had FiiO used USB PD over Type-C for power too, but there will be audio purists who will find this suggestion heinous. Most of my testing was done with the power and data cable plugged in on the back as seen above, with the two outputs in the front going to IEMs and headphones depending on my preference/use case. At this point, press the wheel on the front to turn the device on and see the FiiO logo light up in light blue in addition to the screen becoming active. The logo is backlit by six RGB LED strips and the default function is to be a visual indicator of playback sampling rate. However, FiiO has decided to give you more control over the actual colors and even add a breathing mode if you wanted to have even more of a light show on your desk than your PC and peripherals already provide. The video above goes over the colors on offer; excuse it being shaky given I was holding my phone in one hand and changing the color using the wheel with the other hand. The screen is arguably more useful here, and you can turn off the LEDs altogether if you find it too much.



That screen also helps provide more functionality on the K11 R2R, effectively blowing the K5 Pro ESS out of the water in this regard. The wheel comes in handy here to access the menu and select the various options available, although the limited real estate means FiiO has had to truncate words significantly. Without the provided user manual on hand, it's almost impossible to say what a lot of these options even do. Thankfully, there is a handy guide in the manual walking you through everything, including selecting the gain level, output mode, oversampling mode, USB class mode, screen brightness and timeout, RGB LED brightness/lighting effect/color, device idle/firmware updater/reset, and finally going back to the main menu where you can use the wheel for volume control itself. For example, the screen above shows the K11 R2R has high gain mode on, outputting line out over the 6.35 mm single-ended output, playing PCM at 48 kHz, and the current volume level is 92 out of 100 steps.


Using the FiiO K11 R2R with Windows 10 or 11 doesn't require any additional drivers, with Windows recognizing the device automatically. We see that the default settings (oversampling mode) provides PCM playback options up to 32-bit, 384 kHz out of the box. The USB bridge comes in handy here, and all your favorite players will recognize the device in WASAPI (Windows Audio Session API) mode accordingly. There should be equivalent drivers pre-configured in newer macOS builds too, but I am not familiar enough to speak on this front.


If you have a device that doesn't accept UAC 2.0, or even if you simply want to try other options, then the FiiO USB audio device drivers will be of interest to you. You can find the installer on this page and the latest version at the time of testing was v5.68.0. Installation is trivial as seen above, and these drivers now allow you to make the most of the FiiO K11 R2R within the Windows operating system.



Installing the drivers creates a new output device in Windows as well as provides access to the FiiO USB Audio Control Panel. Just be sure to set the format to your desired level and choose the ASIO (Audio Stream Input/Output) buffer size that suits your latency requirements. With that done, go to your media player of choice. I demonstrated above with JRiver again and set the audio player to the same output. At this point, you can implement further tweaks, but those are player dependent. For example, we see the ASIO drivers are also recognized by Roon, which is quite possibly the best thing you could have if you tend to go with local storage of music files over streaming. I have more or less replaced JRiver with Roon now for its various features and, If you are interested to give it a try, you can use this link to get a free 30-day trial (I don't get anything out of it). There is no first-party mobile app or desktop EQ support here, but you can always use your own EQ/DSP programs as usual.

Audio Performance

Now that we have gone through the capabilities and set up of the FiiO K11 R2R, let's talk more about its capabilities in terms of driving headphones. The K11 R2R generally has worse objective measurements compared to the K11 with its Cirrus Logic DAC, which itself is not a surprise to anyone who has used R2R DACs and tube amps. Funnily though, the output impedances here are lower than on the K11! Regardless, FiiO is marketing an adaptive impedance setting allowing you to use the device transducers rated for as low as 8 Ω impedance and going up to 350 Ω. This is not ideal for ultra-sensitive IEMs from the likes of Campfire Audio, PMG Audio, Vision Ears etc. thus, there is a definite noise floor present with such sets that will get distracting. Power output is highly respectable thanks to the three gain levels and also individual volume curves associated with them, meaning it's not just a defined +/- dB level separating these gain levels. It makes the K11 R2R more useful too, with the low gain setting providing a larger range of volume control than even the more expensive FiiO K7 and K9, as well as several other competing sets in the same/higher price range. The K11 R2R can provide up to 660 mW @16 Ω, 460 mW @32 Ω, and 50 mW @300 Ω per channel off the 1/4" jack, with the equivalent numbers being 520 mW @16 Ω, 1.3 W @32 Ω, and 220 mW @300 Ω per channel for the 4.4 mm balanced output. Note that these are the max power ratings in the high gain mode so you can of course turn things down in lower gain settings. I had no issues using the K11 R2R with just the single-ended output for most IEMs and headphones on the market, including the recently reviewed FiiO FA19 as well as some higher impedance headphones such as the FiiO FT3. More demanding headphones can take advantage of the balanced output, and I found better synergy with headphones that are tuned more neutral-bright. Ironically, this means the K11 R2R worked better for me with non-FiiO headphones which tend to be warmer in presentation. Regardless, the best way to go about it is start off with low gain and work your way up only as needed to ensure you don't damage your ears or connected devices while also having a larger range of volume control.


I spent a couple of weeks using the FiiO K11 R2R with a variety of headphones and IEMs to fully test how it sounds, knowing already that it's not going to work best with ultrasensitive IEMs as well as extremely hard to drive headphones. The line out and preamp features worked very well, and I have no complaints on that front having used this with some active speakers. R2R DACs are not going to be the cleanest sounding, and I'd say this is a basic implementation which doesn't give you that organic taste higher end R2R DACs do. There's a sense of warmth overall, and vocals feel more lush in the foreground. I mentioned above how this is best paired with neutral-bright headphones and IEMs as a result. The NOS mode in particular gives you more of this, but adds further to the background noise with more sensitive transducers. OS mode cleans things up significantly, and yet at this point it doesn't feel much different from a portable DAC/amp or even the K11 with its CS41398 DAC, which is arguably a good thing in that you can choose between two flavors of sound—subtle as they may be. I see what FiiO is going for here though, and there is certainly merit to trying out an R2R DAC if the price is lucrative enough.