FiiO has had a very busy 24 months introducing a complete range of Dongle DACs, desktop amplifiers, DACs, IEMs, and headphones. The Chinese manufacturer has carved out a rather impressive slice of the pie in the desktop and portable audio categories and we continue to be impressed by the build quality, connectivity options, sonic performance, and overall value of its products.
These guys really know what they are doing and a quick look through our extensive list of reviews only confirms that they understand that their products have to be excellent to be competitive in a world where Schiit Audio, Topping, Astell&Kern, Questyle, and Cayin offer something for almost everyone.
Building on the previously released K11 desktop headphone amp, FiiO has announced its successor, the K11 R2R. You can also connect it to your home audio system and take advantage of its new and improved DAC functions from sources connected to the USB, digital optical, and digital coaxial inputs.
What’s New
On the outside, the K11 R2R and K11 look identical but FiiO made some changes on the inside.
24bit R2R DAC Resistor Arrays: This FiiO in-house developed feature incorporates a four-channel differential 24bit R2R (resistor-to-resistor) DAC. The DAC consists of 2 x 48 precision thin-film resistor arrays per channel, totaling 192 resistors with 0.1% tolerance and low-temperature drift (30ppm). What this means is that the circuitry is designed to deliver lower noise and less FFT (Fast Fourier Transform) harmonics to deliver a smooth, rich, and highly musical sound signature.
4-Channel Volume Controller: Complementing the DAC is a 4-channel electronic volume controller. This is designed to deliver both low distortion and low noise, allowing for a highly precise volume adjustment. The K11 R2R includes 3 independent gain levels and volume curves (High, Medium, and Low). This is designed to deliver a better listening experience with various types of headphones – whether sensitive earphones or harder-to-drive over-ear headphones.
Newly Designed Audio Path Circuitry: The source audio signals are transferred via a USB interface processor to a digital audio bridge. After being processed by a Field Programmable Gate Array (FPGA), it is sent to the R2R DAC for 4-channel output after decoding.
The signal then passes through two OPA1642 op-amps for low-pass filtering and single-ended analog signal conversion, before transmitting to the NJW1195A electronic volume control chip for precise volume adjustment.
The output stage of the K11 R2R uses two SGM8262 op-amps for 4-way phase inversion and amplification, resulting in both single-ended and balanced output signals
Tech Note: What an op-amp is
Dual NOS/OS Mode: The FiiO K11 R2R users have the option of choosing playback via NOS (Non-Oversampling) or OS (Over-sampling) Modes. NOS Mode has been designed to maintain the original sampling rate for decoding, while the OS Mode upsamples audio to a high sampling rate of 384kHz.
Easy Control: Designed to ensure convenient feature access, the K11 R2R’s multi-function volume knob is used to power the device on and off, access menu operation, volume adjustment, and more. Power Out (PO), Pre-out, and Line Out (LO) modes can be selected by double-pressing the knob, making it easy to connect to different audio setups.
RGB Lighting: The FiiO logo on top of the K11 R2R is illuminated with RGB lighting, giving a quick way to identify the sampling rate of the current audio being played back. Brightness, color, light patterns, and on/off options are all adjustable within the menu.
Comparison
| K11 R2R (2024) | K11 (2023) | |
| Price | $169 (US) | $129 (US) |
| Product Description | Desktop Headphone Amp | Desktop Headphone Amp |
| DAC | Fully Differential True 24-bit R2R Resistor Arrays | CS43198 |
| Main Control Chip | GD32F303RET6 | GD32F303RET6 |
| Output (6.3 mm – Single-Ended) | L+R > 460mW+460mW (32ohms, THD+N < 1%) L+R > 50mW+50mW (300ohms, THD+N <1%) | L+R > 520mW+520mW (32ohms, THD+N < 1%) L+R > 60mW+60mW (300ohms, THD+N <1%) |
| Output (4.4 mm – Balanced) | L+R > 300mW+1300mW (32ohms, THD+N<1%) L+R > 220mW+220mW (300ohms, THD+N<1%) | L+R > 1400mW+1400mW (32ohms, THD+N<1%) L+R > 250mW+250mW (300ohms, THD+N<1%) |
| Inputs | 1 x USB Type-C 1 x Coaxial 1 x Optical | 1 x USB Type-C (USB2.0) 1 x Coaxial 1 x Optical |
| Outputs | 1 x 6.35 mm (Single-ended) 1 x 4.4 mm (Balanced) 1 x L/R RCA 1 x Coaxial | 1 x 6.35 mm (Single-ended) 1 x 4.4 mm (Balanced) 1 x L/R RCA 1 x Coaxial |
| USB Input Decoding | PCM: 384kHz/32-bit DSD: 256 | PCM: 384kHz/32-bit DSD: 256 |
| Coaxial Input Decoding | PCM: 192kHz/24-bit | PCM: 192kHz/24-bit |
| Optical Input Decoding | PCM: 96kHz/24-bit | PCM: 96kHz/24-bit |
| Line-out (LO) Mode | Yes | Yes |
| Power Out (PO) Mode | Yes | Yes |
| Display | 1.1-inch LCD VA Segment Display | 1.1-inch LCD VA Segment Display |
| Adjustable RGB Lighting | Yes | – |
| Dimensions | 147 x 133 x 32.3 mm 5.8 x 5.24 x 1.27 inches | 147 x 133 x 32.3 mm 5.8 x 5.24 x 1.27 inches |
| Weight | 420 g 15 oz | 407 g 14.36 oz |
| Available Colors | Obsidian Black Midnight Silver Red (coming later in 2024) | Obsidian Black Midnight Silver |
What’s different?
- Appearance: K11 R2R comes with R2R logo while K11 does not have. Otherwise look the same.
- Internal circuitry: K11 uses CS43198 as the DAC chip, while the K11 R2R uses sign-magnitude R2R as the DAC chip. Some of the corresponding circuits are slightly different.
- Parameters: The THD+N & Noise and noise floor of K11 and K11 R2R are nearly the same.
- Software settings function: K11 uses the CS43198 as DAC chip so it comes with a filter setting function. The K11 R2R uses sign-magnitude R2R as the DAC chip, so it has no filter function and the filter setting option is removed. But the oversampling mode and smart idle function are added for K11 R2R.
Initial Impressions
FiiO has become one of the most impressive brands in desktop and portable audio and there is no question that it designs innovative products that offer a multitude of connectivity options, excellent sonic performance, and great value for the money.
Why pay hundreds or thousands or hundreds of thousands of dollars for a DAC/Headphone amp or similar device when somebody like WiiM, Schiit Audio, or FiiO can provide what you need for a lot less – and with their compact size – somewhat portable?
You might still prefer something more expensive, but the FiiO K11 R2R appears to be worth considering.
Price & Availability
The Obsidian Black/Midnight Silver versions of the FiiO K11 R2R are available for $169.99 at HiFiGo.
The previous K11 (2023 model) is still available for $129.99 at Amazon.
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