XI Audio K-DAC

XI Audio K-DAC is an R2R DAC that is their second attempt into the DAC market, after their flagship Sagra DAC. It's priced at $2584.

Introduction

XI Audio is a Taiwanese company specializing in the production of high-quality audio electronics. Their offerings include the extremely popular and excellent Broadway series amplifiers and their flagship Formula S. They also have the R2R Sagra DAC in their lineup, which has gained recognition from many around the world.

XI Audio may be known for its close collaboration with American headphone manufacturer Abyss Headphones, but they have certainly earned recognition for producing phenomenal audio devices in recent years. Of course, XI Audio offers more boutique devices, mainly due to their price, but if you are looking for high-end electronics for headphones, this is a company that should definitely be considered.

Now, XI Audio has released another, this time cheaper R2R DAC model called the K-DAC. With a circuit designed on custom order specially tailored for XI Audio at the legendary Soekris company, we can be sure of the sound quality. Its footprint, which perfectly fits amplifiers in the Broadway series, makes it the ideal, high-end DAC for the desk.

Also, you know me, I’m an absolute fan of R2R DACs, so this one is insanely interesting for me personally. Let’s dig right into it.

Packaging

There isn’t much to say in terms of the unboxing experience of the K-DAC, because I only received the device with a remote control, without the original packaging.

Nonetheless, this is a desktop DAC, so you shouldn’t really expect a luxurious unboxing experience. At the end of the day, the box will probably end up at your attic or in your closet, so that would have been pointless for the company to charge you extra for fancy packaging that you won’t be using anyway. 

Tech, Build Quality and I/O

The XI Audio K-DAC is a high-end digital-to-analog converter that utilizes R2R ladder technology from the renowned Soekris company. The K-DAC was designed with this technology on special order from Soekris, ensuring that it delivers top-quality sound.

R2R DAC technology, also known as resistor ladder DAC technology, is a method of digital-to-analog conversion that utilizes a resistors set to create a precise and accurate conversion process. This technology has been around for quite some time and has been utilized in various forms of audio equipment, but it has seen a resurgence in popularity in recent years due to its high-quality sound and ability to deliver a very unique timbre.

Another advantage of R2R DAC technology is its ability to deliver a more analog-like listening experience. Digital audio can sometimes lack the warmth and richness of analog sound, but R2R DAC technology helps to bridge the gap by creating a more organic, natural sound. This can be especially appealing to those who prefer the sound of vinyl records or other analog audio sources.

In terms of how the technology works, a R2R DAC utilises a set of resistors for the conversion. There are two values: R and 2R (two times R) hence the name. They are arranged in a string of series and parallel connections, which on schematics looks like a ladder, which is a second name for those circuits. This is the oldest type of DACs used in audio. The first converters like this were integrated circuits named TDA1540 and TDA1541. They were used in the first CD players. Nowadays, discrete (made out of single resitors) R2R circuits are used as that allows for much greater flexibility in design. The circuit used here is a combination of FPGA (digital filters and modulators), a set of switches, and obviously a R2R resistor network. This solution was created by Soekris Engineering and is very well known in DIY community.
 


Overall, R2R DAC technology is a highly effective method of digital-to-analog conversion that is worth considering for those who value precise and accurate sound with a more analog-like listening experience. Its ability to deliver high-quality sound and a natural, organic sound make it a popular choice for audiophiles nowadays.

Overall, the XI Audio K-DAC is a great choice for those looking for high-quality sound and a range of connectivity options. Its R2R ladder technology from Soekris ensures precise and accurate sound, while the variety of I/O options makes it compatible with a wide range of digital sources and audio components. Its minimalistic design and compact size make it a great addition to any home audio setup.

As far as the I/O goes, the K-DAC is equipped with USB, Coaxial, Optical, I2s, BNC, and AES-EBU digital inputs, so pretty much everything you would ever need. On the other hand, it offers a pair of RCA outputs, as well as balanced XLR ones, to give you full flexibility when it comes to connecting the DAC to any audio device you’d like. 

The build quality is solid, but nothing incredibly sublime or unique. Its finish is matte, the fit and finish are both excellent, but the entire device looks modest and understated, which can be a good thing for many. One thing that I don’t really like is again, the power switch on the back panel. I had the same issue with the exceptional Broadway S, as it makes it a lot less convenient when powering on/off the device. Other than that, the entire physical aspect of the K-DAC is solid, and you simply cannot nitpick anything else in my opinion.

Sound

In the world of more and more affordable Sigma Delta DACs, a $2500 R2R DAC is certainly a rarity, hence this sound description was really interesting for me to do. I’ve always been a fan of R2R DACs, as I’m a vinyl fan and I’m used to a rich, smooth, and analog sound. Of course, as a reviewer, I always have to put my personal taste aside, but let’s be honest – it’s not entirely possible.

You see, you can go and buy a $200 DAC that will measure exceptionally well and call it a day. However, this kind of device isn’t meant for all of you that went into the high-end audio market and you’re looking for specific sound characteristics. R2R DACs have that rare ability to deliver a beautifully rich and analog-like sound that is incredibly addicting and just fantastic to listen to. It’s a perfect marriage of technical capabilities and timbre that feels like you’re not listening to digital audio.

Overall, the biggest strength of the K-DAC when it comes to its sound is the fact that it doesn’t overdo anything, nor is it bland. High-End devices have to offer unique yet refined sound characteristics to be valuable to the audio market nowadays. The Chinese competition became so strong, that putting a hefty price tag and pretending that nothing happened would have been devastating for any manufacturer these days.

Luckily, XI Audio is definitely not interested in manufacturing audio devices that are just expensive. There’s a lot of thought behind their products, and while not really affordable, they do offer exceptional quality and technology to justify the price. Let’s dive right into it, and let’s start with the bass.

The XI Audio K-DAC offers the fantastic sound quality, and its bass performance is particularly noteworthy. The K-DAC’s bass has an incredible level of detail, control, and richness, making it a standout performer in this regard. One of the key features of its bass is its incredible detail. The bass is extremely well-defined and articulate, with a level of clarity that is rarely heard in other DACs. This makes it ideal for music that has complex bass lines, as the K-DAC is able to accurately reproduce all of the nuances and subtleties of the music. In addition to its detail, the K-DAC’s bass also has excellent control. The bass is tight and well-controlled, with a strong sense of precision and definition. This makes it ideal for music that requires a strong and punchy bass, as the K-DAC is able to deliver the impact and power needed to make the music come to life. The bass is also rich and full-bodied, with a warm and musical character. This makes it ideal for music that requires a more laid-back and relaxed bass sound, as the K-DAC is able to deliver a smooth and enjoyable listening experience. One song that really showcases the K-DAC’s bass performance is “Lateralus” by Tool. This track has a complex and technical bass line, and the K-DAC is able to reproduce it with incredible detail and control. At the same time, the K-DAC’s rich and full-bodied bass adds a sense of musicality to the track, making it an enjoyable listen. It’s not easy to keep up with the Octopus (Danny Carey) himself, but the K-DAC is worthy of this god-tier musician. Overall, the XI Audio K-DAC’s bass performance is truly impressive, with incredible detail, control, and richness. It is able to sound both technical and musical at the same time, making it a standout performer in this regard.

In addition to the bass, the K-DAC also excels in the midrange. The tonal balance of this DAC is spot-on, with a natural and realistic representation of the various instruments and sounds in your favorite music. This makes for a truly immersive listening experience, as the K-DAC brings the music to life in a way that feels authentic and true to what’s been recorded. Another area where the K-DAC shines is its beautiful vocal reproduction. Whether you’re listening to a soft, intimate ballad or a high-energy rock song, the K-DAC captures the full range of vocal expression and emotion. This is particularly evident in the song “Wanderings” by Lunatic Soul, where Mariusz Duda’s warm and romantic vocals are reproduced with stunning accuracy. The K-DAC captures the depth and richness of Mariusz’s voice, making it sound like he’s singing right in front of you. This is a combination of accuracy and emotions that you’ll never find in an affordable Delta Sigma DAC. This is the main reason why R2R DACs are so popular among high-end audio geeks, as it just gives you the best of both worlds. 

Now let’s move on to the treble. The XI Audio K-DAC offers a treble that is direct and clear, certainly not dark or softened. The treble is very accurate, sparkling, and well extended, but never sharp or artificially sounding. This is especially important in poorly produced music, as the K-DAC will not make poorly mastered albums sound aggressive or unpleasant. It may not add much of itself, but it is also a safe and enjoyable choice. Again, the fantastic detail retrieval makes it sound incredibly open, fast, and entertaining, with the natural timbre of the instruments and every small detail preserved. Hi-Hats have excellent thickness and reverberations are clearly marked but not exaggerated. Keep in mind that this is definitely not a dark sounding piece of gear, and it is definitely not meant for those who would like their treble to be on the softer, calmer side. This is all about transparency, accuracy and lightning fast decays, and if you’ll play a well-mastered album on this DAC, you’ll be amazed. 

Lastly, the soundstage. The K-DAC has an ability to create a vast and accurate stage with exceptional level of accuracy and a very natural size of the soundstage itself. It doesn’t sound intimate nor overly roomy, but rather it sits in the middle of what you’d call a “natural” soundstage reproduction. This is highly important in a high-end piece of gear that is meant to offer an amazing quality without sounding like it’s trying too hard. This is the biggest difference between a good DAC, and a great one. Where the Topping D90se struggles hugely with its soundstage depth (or should I say that it basically doesn’t exist), the K-DAC has a sophisticated depth reproduction that will never try to fool you with its overly deep presentation. Everything just sounds like it’s supposed to, and this is what this level of audio gear is all about.

Pairing

Feliks Envy

This is peak headphone audio that is at my disposal at this moment. These two pairs exceptionally well, and neither of these devices tries too hard to make the music sound “different”. The Envy is just a top-tier, 300B amplifier that offers a crazy bass impact and incredibly rich tone, and together with K-DAC’s excellent tonality and fantastic technicalities, it makes for one hell of a combo. Listening to the Hifiman Susvara or Meze Elite via this setup is an experience that you should try at least once in your lifetime. The music feels incredibly real, but there’s a sense of fun to it as well, as the sound reproduced by this setup is dynamic, rich, and accurate at the same time. Brilliant.

XI Audio Broadway S

Now let’s look into the dedicated amplifier for the K-DAC, the Broadway S. This is a battery-operated amplifier that has been reviewed here.

And yes, this is a dedicated amplifier for this DAC, and after trying it, you immediately know why. These two pair beautifully, creating a very engaging, almost spectacular type of sound. The soundstage, the treble presentation, bass impact, note weight, decays…everything sounds insanely good, especially when paired with TOTL IEMs like the Fir Audio Kr5, Xe6, or the Campfire Supermoon. While this combo doesn’t have enough power to run headphones like the Susvara, it is just perfect for efficient planars or IEMs. 

The only con that I have to mention is that even though these two are meant to work together, the finish of both of the devices is quite different, resulting in a look that could have been more uniform. As you can see in the picture above, the finish is quite different, so keep that in mind if you are really sensitive to “identical” looking stacks.

Hifiman Susvara

The XI Audio K-DAC might be just the perfect DAC for the Susvara in its price range. Its highly sophisticated and technically impressive sound that has that hint of r2r goodness makes the Susvara sing. The K-DAC also offers a great bass impact that the Hifiman flagship really needs to sound its best, as it’s definitely not the hardest-hitting flagship on the market by any means. Still, the level of detail and resolution of the K-DAC paired with the Feliks Envy gives the Susvara all the necessary qualities to show its best-in-class technicalities, and it’s paired with great tonality and dynamics with this combo. 

Meze Elite

Now onto the Meze Audio flagship Elite, which offers a more relaxing, softer type of sound when compared to the Susvara. This is a fantastic combination as well, as the Meze further improves on that R2R tone with its sublime, natural, and romantic tuning. This combo might not offer the BEST detail retrieval, but it is just so pleasant to listen to. Actually, the K-DAC paired with Envy and the Elite is my nr.1 setup for late-night listening after a long day, when I value a relaxing, smooth listening experience the most. This shows how incredibly flexible and valuable the K-DAC is, as it basically does it all.

Comparisons

EarMen Tradutto

Let’s compare the K-DAC with our “Best DAC 2021” – the EarMen Tradutto. While the Tradutto offers a tone that might be quite similar to a classic r2r timbre, it just cannot beat the real deal. The K-DAC sounds more detailed for sure, but it also offers a richer, more analog-like tone that is just reminiscent of the R2R legend. 

There’s also a big price difference to have in mind, sure. The Tradutto is still incredibly good, and its biggest competitor (Topping D90se) still stands no chance when compared with the Tradutto in my opinion. Yet, while paying extra for the K-DAC, you’re simply getting a more mature and better-sounding DAC that will pair much better with TOTL gear.

Hifiman EF400

Both the EF400 and the K-DAC are R2R DACs, so this comparison simply had to be done. The EF400 is a fantastic, affordable piece of gear that we recommend over and over again, but when compared to the K-DAC, it’s easy to hear that it’s just an entry into an R2R world. The K-DAC just offers much more detail retrieval, better resolution, better soundstage, and a more pleasing tonality that sounds more natural.

This shows what you should have expected – the EF400 is still a fantastic option in its budget, but it cannot compare to standalone R2R DACs that cost a couple times more. Thankfully, there’s a big difference in sound when you’re paying extra.

Summary

The XI AUDIO K-DAC is the second XI AUDIO device that we’ve reviewed at Ear Fidelity, and I certainly hope that it isn’t last. XI Audio once again proves that they offer an exceptional audio gear that while expensive, is definitely worth its asking price when you take the sound quality into consideration.

The K-DAC is everything a $2000 R2R DAC should be – incredibly accurate, fast, detailed, but also highly musical, smooth, natural and rich sounding. While the build quality is nothing to write a book about, the sound alone leaves me no choice but to recommend trying the K-DAC. From now on, this is the best DAC that we’ve got access to and it’s going to be our reference for high-end DACs in the future to come.

Highly Recommended.

Big thanks to XI Audio for providing the K-DAC for this review. I wasn’t paid or asked to say anything good or bad about this product, all of the above is just my personal, unbiased opinion. XI Audio hasn’t seen this review before publishing it.

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