Closer Examination

The FiiO K11 R2R is a desktop class DAC/headphone amplifier combo device, akin to some others we have seen before from FiiO. But this is also the smallest desktop FiiO source I've tested to date, and I dare say most people will be left bemused when they first see this tiny thing in person. At 147 x 133 x 32.3 mm and weighing just over 400 g, the K11 R2R is going to make it easy for you to place it anywhere on your desk, including under the monitor if you so prefer. A plastic body would have made it lighter, but I actually appreciate FiiO continuing to use anodized aluminium for the chassis which ensures the K11 R2R does not slide around easily or get lopsided with a cable on the front and/or back, in addition to helping dissipate heat. The K11 R2R comes in black or silver colors for now, and there is a red version planned soon too. The device is intended to be used in a horizontal form factor, allowing for the FiiO logo on the top to shine through—literally. Helping differentiate this from the FiiO K11 is the R2R branding on the top too, and then we move to the front where you will see a 6.35 mm single-ended headphones output, a 4.4 mm balanced headphones output, a small high-contrast LCD screen (so there is no burn-in fear), and a knurled multi-function wheel on the right side. Purely by the addition of the screen and the balanced output, the K11 R2R is a good upgrade to the K5 Pro ESS it aims to replace.


A look from the side shows no ventilation at all, making this a solid chassis and thus indicating the K11 R2R is not expected to suffer from thermal throttling. There is more I/O on the back in the form of the 12 V DC power input, a USB Type-C digital input, optical input, a coaxial input/output, and line outputs via RCA. There is no dedicated on/off switch on the back, although the wheel on the front presses in to also act as a power switch. Likewise, I like that we've stepped away from USB Type-B here, with the modern Type-C port making more sense in 2024. The other options are also nice to see here, allowing for the K11 R2R to also work as a speaker preamp or just a DAC too. We don't get higher end features here, be it inputs such as Bluetooth, HDMI and I2S, balanced outputs in the form of dual 3-pin XLR, the ability to connect to external clocks, or a ground/lift switch as we saw on the flagship K19. This helps maintain the K11 R2R's status as a more entry level source in FiiO's desktop line, and yet I dare say the vast majority of readers here will not find the K11 R2R lacking for their use case.


The underside of the K11 R2R shows FiiO is using a two-piece chassis, with the bottom panel secured using six Phillips head screws. It also has a raised section with a silicone rubber contact surface, thus adding further grip against your desk and preventing scratches to the metal body. Taking off this panel is simple enough, although we see a lot of what makes the K11 R2R tick is on the other side of the PCB, and that is not as easy to access in a non-destructive manner. The back side shows relatively clean construction, and what looks like a budget potentiometer/encoder that is also a volume wheel—among other things. Thankfully, volume control and channel balance is significantly better than it could be owing to the use of a Nisshinbo Micro Devices NJW1195A 4-channel resistor ladder electronic volume controller. FiiO has the audio schematic up on the product page, which is handy to know more about the K11 R2R. True to its name, it employs a custom 4-channel 24-bit R2R DAC with 96 thin film resistor arrays per channel. This is different from going with a third-party solution from the likes of ESS, AKM, ROHM etc., as is usually the case with the vast majority of sources sold today. This means natively you have up to 24-bit, 384 kHz PCM and DSD256 decoding, The K11 R2R also uses a GigaDevice GD32F303 32-bit ARM-Cortex M4 SoC, a Savitech SA9312L USB audio bridge, two Texas Instruments OPA1642 low-pass filter op-amps, and finally two sets of SGMICRO SGM8262-2 op-amps for audio amplification.