FiiO K11 R2R desktop DAC/headphone amplifier

Having just reviewed the astounding FiiO FA19s, it is time to look at the headphone amplifier that has been in heavy rotation in the last two months; this is the ‘WiiM’ of desktop headphone amplifiers.

Design

This FiiO K11 R2R desktop DAC/headphone amplifier is packed with technology at a competitive price. The FiiO site has a mind-numbing amount of information on a £150 DAC; if you are that inclined, the link is here.

The FiiO K11 R2R features discrete R2R DACs with a simple architecture of resistors arranged in a ladder network. This DAC arrangement should deliver excellent linearity, meaning they can accurately reproduce the input signal to the analogue without introducing significant distortion. Because of this linearity, R2R DACs are often found in high-end audio applications for their transparency and ability to preserve the original signal’s integrity.

Another advantage of R2R DACs is that they are inherently fast and do not require extensive oversampling. Without complex algorithms, they can directly convert the input signal into an analogue output. Finally, such DACs operate without a feedback loop, allowing for faster switching speeds and reduced latency, making them suitable for high-speed applications.

The main inputs are to the rear; the FiiO K11 R2R has 12 V DC input, USB C, Optical In, and Coax In/Out. Outputs are analogue to RCA line out at the rear, and headphones are 4.4mm and 6.35mm at the front. Additionally, there is a Coax output, though I cannot think why. The volume knob on the front to the right acts as volume control and On/Off. It also leads to various gain stages and sampling options (including DSD).

Quality

The K11 has a solid aluminium alloy body that feels weighty for its size. The unit has a CD-sized footprint, though it is square and about 3CDs high. The unit rests on a rubber octagon-shaped base. On the top is a logo that changes colour based on the sample rate input. The front of the unit has a simple LED screen with primary sample data and access to the menu system that is controlled by the volume knob, which clicks nicely.

The box contains the K11 R2R unit, a USB data cable, a 12V power cable and power adapter, a 6.35mm to 3.5mm headphone adapter with a quick start guide, and a warranty card.

The full specification is here.

The FiiO K11 R2R costs £150 (October 2024) and is available in silver and black, and a red version is coming.

Performance

Review Equipment

I’m listening to the FiiO K11 R2R with a pair of Meze Audio ADVAR in-ear monitors, the FiiO FA19 in-ears and the Meze Audio 109 Pros, as well as a newly arrived (and run-in) pair of Focal Azurys.

I also just received a NuPrime 12V DC power supply, which I will comment on, using it in place of the supplied power supply.

Physically

The unit is a joy to use. On the top is a logo that changes colour based on the sample rate input (this is programmable). This is very cool, but the novelty wears off fairly quickly once you’ve played your sample rate ladder playlist (96kHz and above, Yellow, 44.1-88.2kHz Cyan, in my case!).

FiiO K11 & R9, Chord Mojo 2

In NOS mode, the sound turns warmer and yet more calm…

The K11 is an excellent handy desktop headphone amplifier, and it is warmer than the FiiO R9, which is also currently on my desk. The FiiO R9 has so much going on that I don’t know where to start if I’m honest. The R9 with the FiiO FA19s is lively; the K11 calms these FA19s nicely and broadly. I prefer the K11 with the FA19s, where the sound relaxes and opens up. There are No Over Sampling (NOS) and Over Sampling (OS) modes. In NOS mode, the sound turns warmer and yet more calm; one may describe this as being analogue. The ADVAR become nicely musical, and this has been my preferred desktop solution recently whilst I’m tapping away.

Due to its simplicity, the K11 is easier to use than the Mojo 2 in many respects, but the Mojo 2 has many more functions. The Mojo 2 is, however, several multiples in price but offers more performance and flexibility.

RCA Out to Schitt VALI

A listen to…1969 track by Creedence Clearwater, Fortunate Son (Qobuz 24-bit, 192kHz), leads to a full-on musical head strut at the desk

Switching the K11 to Preamplifier mode sends the analogue output to the RCA at the rear, and feeding that to my cheap Schitt VALI3 tube headphone amplifier (£130 delivered) is an absolute delight. The analogue output from the FiiO K11 flicks to full volume output, but this is still managed by the volume knob at the front. A listen to a classic 1969 track by Creedence Clearwater, Fortunate Son (Qobuz 24-bit, 192kHz), leads to a full-on musical head strut at the desk; I hope no one is watching. Here, I have the Meze Audio 99 Neo, which is clean, crisp, and analytical yet softer with the VALI 3.

I acknowledge this is an odd collection of boxes, but it works for me. The VALI 3 is terrific fun here, and the K11 is a perfect platform.

NuPrime 12V DC power supply

…an uptick in midrange clarity with the 109 Pro headphones.

Swapping in the NuPrime 12V (there is a 5V version, by the way) power supply for the wall-wort supplied by FiiO certainly cleans things up for me, with an uptick in midrange clarity with the 109 Pro headphones. I wouldn’t advocate purchasing a power supply costing twice as much as the DAC/Amp in question, but there is a lot here in performance terms with the K11; so, if you can afford to clean up the power supply, then why not? Credit goes to the K11 for being capable of delivering the performance upgrade.

ADMM (Audiophile Digital Music Masters) is the UK distributor for the NuPrime 12V supply, and the UK SRP is £449.

Thoughts

… at £150 this is a total desktop winner …

Considering the popular desktop headphone amps at differing price points, the Chord Electronics Hugo 2, nearly £1800, is the near-perfect performance choice. But the budget is key. Offering more value is the more portable Chord Electronics Mojo 2, which is almost £400. But at £150, this FiiO K11 is a total desktop winner, and the likes of Audioquest must be quaking in their boots with this level of technology near their price points (Dragonfly Cobalt £180, Red £160, Black £90). Yes, the K11 needs a cable from a USB rather than slotting straight in, but it is quite a simple and elecgant solution. The same thoughts occur with the terrific but lively iFi hip-dac 3 (£199), not forgetting the iFi Zen DACs (the new v3 is £229, the v2 is £199).

There is a FiiO streamer to match, the FiiO SR11 (£99!), which has the same form factor and thus reminds me not only of the Outstanding Zen stack but also of the Earmen headphone stack that was thrilling in 2022—and that received an Editor’s Pick.

Overall

This is an easy headphone amplifier entry point. With a low price but high performance, the K11 is hard to find fault with.

Specification

Full details are on the company’s site. https://www.fiio.com/k11r2r