A Survey of Digital Audio Players Part 1 Calyx M


Calyx M
For most audiophiles, the first exposure to Korean firm Calyx came back in 2011 with their highly regarded "24/192 DAC". What most people (myself included) didn't know is the company actually started way back in 1999, as a fabless semiconductor company working on proprietary PWM and class D amplification. So Calyx has a lot more industry experience than many people know about.

Apparently not content with their several recent products in the traditional 2-channel space, Calyx decided to attack the personal audio segment by releasing a flagship DAP. Dubbed the Calyx M, this $999 device aims to compete with the top audiophile DAPs on the market, regardless of price. Does it succeed?

External Design
The Calyx M is a very straight forward design. When viewed head on it basically looks like a modern smartphone. Change angles and you'll spot the difference—at nearly 15mm, the depth is over twice that of an iPhone 6. Weight is substantial as well, a hefty 230 grams. To put that in perspective, an iPhone 6 is 129 grams, and the Sennheiser Momentum headphones are 190 grams. So the Calyx is in a whole different league compared to the diminutive Sansa or Sony models we've discussed so far.

I dig the feel of the M—it has a solid heft to it, with a substantial aluminum body and nicely laid out transport buttons on the side. The volume slider is unique in being magnetic rather than permanently connected. A gimmick? Maybe, but it feels smooth during use so I'm on board with it. Users can opt for software control if they prefer. Display is listed as 4.65 inches, virtually the same size as many phones including iPhone 6 and numerous Android models. Calyx went with a Samsung OLED model and I find it quite pleasing to the eye. Resolution is 1280 x 720 which is merely average when judged in smartphone terms, but perfectly adequate for this application. I do have a few gripes with the user interface but display quality certainly isn't one of them.

Internal Design
The M sports some nice audio hardware—ES9018-K2M Sabre DAC chip feeding a discrete class A output stage—based around a decent if not overwhelming platform featuring a Cortex A5 CPU (as found in the iPad 2). It can handle almost everything you could ask for in terms of playback, from "lowly" CD quality 16-bit/44.1kHz to the latest DSD128 and everything in between. Output impedance is right around 2 ohms so the M can handle low impedance, multi-BA driver IEMs without issue.

The main surprise here is the class A output stage which gets the device slightly warm to the touch during extended listening. Given the company's history in PWM amplification I would have assumed that would be a natural choice, putting the device somewhat in line with the Sony in that aspect. What we get instead is a fairly potent "traditional" amp which sounds excellent, but may be partially to blame for the mediocre battery life. More on that shortly.

User Interface
Like the competition from Astell&Kern, Calyx started with Android and skinned it so heavily as to be barely recognizable. There are a few hints, such as the pop up window second guessing your command to power down. But in general I'd say the average non-techie user might not make the connection. The first time I used the device it was rather underwhelming in terms of speed. Transitions were choppy and delays were frequent and frustrating. Unfortunately it felt like yet another botched UI attempt from a high-end DAP—perhaps more ambitious than most, yet not much more successful.

Fast forward to now (several firmware updates later) and things have really improved. The UI is generally smooth and stable, with just the slightest bit of choppiness once in while to remind us of the relatively modest CPU on board. While not being quite as intuitive as the AK240 or even the Sony A17, Calyx still does a good job overall. It's easy to navigate, with emphasis on swiping rather than button mashing (but only when it makes sense to do so). The M also makes good use of screen real-estate by showing thumbnails while scrolling through music.

One complaint I have is how it rescans the library after each reboot. This has been a complaint going back quite some time, and Calyx really should have taken care of it by now. A big strength of the M is the ability to accommodate large collections via its dual SD card slots plus generous internal memory. Encouraging massive libraries yet unnecessarily scanning after every boot seems rather counterintuitive.

Overall, the M user interface is still plenty satisfying. It trails just a bit behind that of the AK240, but not by much, and with some firmware tweaks I could see it catching up for the most part.

Calyx made a wise choice here by offering not one but two expansion slots—one for full sized SD cards, and one for microSD. There's also 64GB onboard storage to get you started. That's enough potential space for a fairly massive library. Some might question the choice of microSD—why not use two full size slots like some of the competition? True, microSD is more expensive, and max capacity tends to be smaller. If I only get once slot I'd prefer regular SD. But having both allows me to play any type of card someone might hand me, so I find the flexibility worth the trade off.

Another wise choice is the ability to run as USB DAC. This essentially turns the M into a desktop DAC/amp for stationary use. Using the XMOS chipset, drivers are required for Windows but not for OSX machines. Bonus points for charging via microUSB rather than a separate port.

Aside from that, things are rather limited—just a single unbalanced headphone jack. There's no dedicated line out, and no digital output either. Calyx seems to be making a statement that their integrated processing and amplification are of sufficient quality that we really don't need to add external devices. And I can't say I disagree.


So far I've been almost totally complimentary of the Calyx M—that ends now. The Calyx M has poor battery life. There's just no way around it. Initial claims from Calyx ranged from 7 hours to as high as 10 hours, which still isn't amazing by any stretch. Instead we end up getting a consistent 4 to 5 hours. No matter how good the device might be, that's low enough to knock it out of contention for a lot of users. To make matters worse, it doesn't seem to have any provision for auto power off. If you forget to power down when you stop listening, the player will be dead by the next time you go to use it. This again seems like a simple thing Calyx should have taken care of long ago.

Sound Quality
The Calyx M sounds excellent to my ears. It has a rich, bold presentation which brings to mind quality desktop gear. I hear a bit of warm character which helps it stand out from the competition. By way of sonic analogy—if the AK240 is a modern DAC with a focus on detail and clarity, the Calyx M is closer to the beefy Parasound DACs of old, with the Ultra Analog R2R DAC chips. It isn't a slow, syrupy sound in the least, yet I do hear a certain thickness of note absent from the AK240. I find this interesting since the M uses an ESS Sabre chip, and some folks tend to characterize the "Sabre sound" as being thin and strident. The M is anything but. Of course, it's difficult to know if the DAC portion or the amp portion is responsible for this character, but either way I quite enjoy it. Details are still plentiful but aren't paraded around as the main event. It's a non-fatiguing sound that I can enjoy for hours on end—assuming the battery doesn't give out on me.

The M is quite versatile as far as headphone pairing. It comfortably drives most cans without much trouble, save for the really difficult stuff. Obviously the HiFiMAN HE-6 is a no-go, and most other planar magnetic models don't seem to hit full stride either. This is not unexpected for a portable device. Dynamic cans work very well—bright headphones in particular get a helping hand from the smooth, creamy sound signature, resulting in a more palatable presentation. It may not be strictly accurate but damned if it isn't pleasing to the ear.

I don't want to overstate this minor coloration. By no means is this a rolled off, dull sounding DAP. It's not even necessarily "dark", but more like just a tad "relaxed" up top. Combined with the richness of the bass and that wonderfully full midrange, the overall effect is what some might call "analog" sounding. Interestingly, detail retrieval remains quite strong, with nuances and micro events still very much in evidence. Of all the DAPs here, this may be the one I most frequently gravitate towards based on sound quality alone.

I've spent considerable time with the original Calyx 24/192 DAC as well as their latest flagship, the $7k Calyx Femto. Both devices have their charm, and I was expecting the M to follow suite in terms of sonic signature. I was pleasantly surprised to hear Calyx do something a bit different with their portable device. The M shares certain sonic traits with the dedicated DACs yet has a warmer tonal balance which, to my ears, is more musical and enjoyable. If their next dedicated DAC goes in this same direction, I can easily see it finding a home in my system.

Jayhawklaw's picture

Hopefully (fingers crossed) the new Astell & Kern AK Jr. will be included.

John Grandberg's picture

I mentioned in the article this is a fast moving segment... it will be hard to keep up with these newly announced models. I think the important thing is to establish a baseline with the main stuff, including a Wall of Fame. That will give us a lay of the land for any future individual reviews to be judged against. Kinda like what we did with custom IEMs.

So far I have enough to expand to three articles (instead of two as originally planned) and that's before adding the newest stuff like AK jr.

Wilderbeast's picture

This site is turning into a useful resource - thanks guys.

I'd like to see the Cowon Plenue P1 included too!

I'm interested to see if there really is a difference between the AK120ii and the AK240. They have the same amp and dac but a very different price.

Akmax57's picture

Has anyone tried the Sony player with the Sennheiser Urbanites? Seems like the warm tonality of the Urbanites and its recessed treble that Tyll had noted, might be a nice match for the Sony and its slightly upper frequency tilt.

The Federalist's picture

Hey John this is a really great review.
Especially since this is an issue I am confronting right now. Whether to retire for good and all my iPod and move to a more upscale portable source like the AK100 V2 AKJR, Pono, or Geek Wave etc.

I actually think a fair number of readers, like myself, would want to use these types of devices as a portable transport that can be connected to an external amp/dac, whether in desktop or portable configuration.

The fact that many OEM's included a digital line out on their devices indicates that they saw this as a likely/possible use of their device as well.

I understand that with the number of devices involved you can't include comments on sound quality in all the different connectivity options like how the X5 or Sony or Calyx sound when externally amped, or when DA conversion is done externally.

But I was curious if in your own listening if you've used any of these as a transport using external converter/ amps and if the sound quality deltas between a high end and lower end (i.e. AK120/240 or Calyx vs. iPod or Sansa Fuse) are less dramatic or disappear if they are used in this capacity.

Any insight would be welcome... and kudos for this review series... The DAP market has been growing stronger and reemerging for a couple few years now (since Apple started neglecting the iPod) and this is the first in depth look at the current state of the art... Good on ya for doing this.


John Grandberg's picture

What you've got there is really two issues - DAPs used as transport, and DAPs used with line out.

Easiest issue first: the differences are fairly easy to spot when using line out to a nice external amp. First off, just getting a true line out with proper voltage is half the battle. That alone separates the more serious contenders from their pedestrian counterparts. Not saying you can't use a portable amp with a Clip Zip in a pinch, but with a reasonably nice desktop amp you'll notice its shortcomings. With an AK100 II, or Pono, or X5, the superior internal DAC quality is noticeable imho. Not sure I'd jump all the way to AK240 just to use it feeding a desktop amp though - it has to make sense for use on the go, and the home use is a sort of bonus in my eyes.

Now, for transport duty, digital out to a DAC, the differences are far smaller. The X5 is the cheapest one I've used to give an easily accessible SPDIF signal (the Sony A17 doesn't make it easy for us), and it works quite well. Depending on the DAC involved, you can do a little better, but the difference is not massive. Then again, choosing the X5 means you are stuck with that interface, so again it's all relative to the larger experience. Keep in mind some models like the Calyx don't have digital out.

The Federalist's picture

That tells me what I need to know... I've been trying to convince myself that I can ditch my iOS devices and my computer completely by buying an AK100 II that would become my full scale source. I could use it as a transportable er umm.. transport. I can plug into my optical input on my dac at work, it'll handle portable duties on the train, and I can plug it in to SPDIF at my home system as well... My entire library travels with me and sounds outstanding anywhere I go.

But I don't know that I need all that yet... May find a jumping off point that is in a bit shallower territory than Astell & Kern... Maybe Cowon J3 or Fiio X3 to start. To see how well a DAP transport integrates and to see how often I reach for it.

Either way this is a great angle you are taking with the review/ roundup... This market is obviously re-emerging with all these new devices hitting the market...



mobbaddict's picture

Like someone else suggested, it would be nice to add some RMAA measurements to those surveys, it would make them more in line with your flawless headphones reviews.

Besides would you care to explain your procedure for these tests? Did you rely solely on your memory or did you make direct comparisons between DAPs? And would you consider doing blind tests as well?

I'm sorry for being so boring but I always take subjective impressions with a pinch of salt when it comes to sources, I believe we always tend to overestimate the actual differences. Last audiophile DAP I bought was a Nationite s:flo2, and it was no better than my current Samsung smartphone in direct comparison.

John Grandberg's picture

I've messed with RMAA extensively and found it interesting but also contradictory. After trying various configurations and getting different results with each test rig, I came to the tentative conclusion that I just wasn't comfortable with the results as saying anything definitive about the gear being reviewed. If this was my own blog I might pick a test rig and run with it - at least the results could be compared with my own prior measurements on the same rig. But next to Tyll's impeccable measurements the whole thing seemed amateurish (at best) and I'm not comfortable putting any stock in it. I may revisit the idea in the future.

My procedure is a combination of extended listening and real-world use along with numerous direct A/B comparisons, level matched but not blind. I feel this best approximates the experience of actual users. I know some people will have issues with my approach and I'm fine with that.

I do agree that the differences are not always as clear as reviewers would have us believe, and I hope never overstate things in my own articles. When I describe the character of these DAPs I hope I make it clear enough that in most cases it's a fairly subtle thing. And as you'll see in my next article, a good smartphone can in fact be a viable alternative in many cases.

Gegliosch's picture

Hi, I'm looking forward to the second part since you posted this. It's been a while - are you still gonna write it?

John Grandberg's picture
Almost done with it, hoping to post within a few weeks. It's taking forever for various reasons but I'll get there. Then on to part 3!
lugh_lampfhota's picture

I purchased my NWZ-A17 a couple of weeks ago and promptly purchased a 128GB microSD for additional memory. I was immediately disappointed when I realized that my Windows 8.1 computer could either see the walkman or the card, but not both. I tried every format option without success.

I contacted Sony support who stated that they weren't very familiar with the device, but after some research, they advised that I could only use the walkman or the card, not both. And further they stated that storing music on the card was not permissible.

If anyone has another experience I'd enjoy hearing about it.


John Grandberg's picture
I sent the A17 back already but I'm almost positive mine didn't act that way. It integrated the library using tracks from internal memory and the microSD. I could browse by artist or album etc and it would all show up on the same list. If I recall correctly it did keep them separate when browsing by folder, which sort of makes sense if you think about it. I use Windows 7 though so that could be a factor.
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