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.

castleofargh's picture

cool to see something about DAPs.
I usually whine a lot when reading reviews as they always are too nice with the devices, forgetting to tell about the shameful side of a device. well I must say, this time the practical reports felt spot on for the stuff I own or could try(and I really don't say that often).

I also wondered about the hm802 not getting much love. it's too big for me, I'd rather have smaller and use an amp when necessary, but it seemed like a pretty good product.

John Grandberg's picture
If everyone writes fawning reviews and leaves out all the disappointing aspects, how will the companies making these DAPs ever learn?
Dopaminer's picture

Great review so far; really looking forward to Part II. I think you should reconsider your iBasso stance and include the DX90. Judging by the headfi threads, the DX50 and DX90 have been the `gateway` daps for many audiophiles who transitioned from smart phones or ipods, and then subsequently `moved up` to higher priced (sometimes MUCH higher priced) daps like AK240, etc. The DX50 and DX90 are highly relevant in any comparison, especially the DX90 with its power and dual sabre dacs, and its huge following.

John Grandberg's picture
I have to admit, I'm still sore at iBasso for blowing out my $750 set of CIEMs with their stupid volume bug. You're totally right about their relevance, but I'm just not sure I'm "there" yet.
tony's picture

Thank you for explaining the differences in all these players.

I'm reading and trying to imagine each player vs. my iMac/Schiit system.

Does anyone offer an iMac in shirt pocket size?

Anyway, nice bit of work here.

Tyll, Joker, Katz and Grandberg make a pretty strong group of journalists.

Tony in Michigan

potterpastor's picture

Tremendous survey so far! I love my Sansa Clip and my Sansa Clip+. By the way, I prefer the sound quality of the original Sansa Clip over the 2nd gen Sansa Clip +, but the original clip doesn't have a slot for micro sd cards.

John Grandberg's picture
I haven't had an original Clip in ages. No memory expansion = no go for me. But it's interesting that you like it more for SQ. I know they switched to a newer AMS SoC for the Clip+ and newer models, so I can see how it might be a little different. Personally I recall them sounding the same but I can't say I spent a lot of time comparing.
potterpastor's picture

The Sansa clip firmware is really sluggish and slow. It takes hours and hours to refresh the media every time you intentionally or accidentally move the microSD card. It is just not feasible.

You didn't review the iPod touch fifth-generation, but it probably is the best of all the players. It is so easy and fast to load music, and it sounds great.

Impulse's picture

I've been using a Clip Zip for running for a few years now, along with a pair of MEElec M6. Tempted to swap them for my Xiaomi Pistons but I like the fit of the M6 a lot when it comes to being active.

I used to take along the Zip when traveling but my Nexus 5 doesn't really burn thru battery much while playing music. I'm usually sending it via Bluetooth anyway to a Sony MW600 receiver (and my V-Moda XS or Ety IEM).

That's one category of devices I'd love you guys to survey, ClieOS tested some of the Sony/Samsung BT receivers on Head-Fi a while ago but it was not an exhaustive review. I feel like they kill two birds with one stone...

It takes the burden of output (DAC and amplification) off your phone or tablet, while also cutting down on wires, particularly when used with something like the XS with removable cables you can swap for short ones.

Impulse's picture

A BT receiver lets you enjoy the headphones you already have with a minimum of wires without getting pricey dedicated BT cans or a compromised set...

It's not something I use at home, at all, because I know BT is ultimately a bottleneck to what my cans are capable of (never mind my Asgard 2); but it's ultra convenient on the go...

As much as Tyll complains about how cramming batteries and BT electronics into a pair of cans tends to hurt their design you'd think these things would've come up in the conversation a few times.

John Grandberg's picture
I have a Noble BTS on the way, hoping it accomplishes just what you mention. From a design perspective it looks like just what the doctor ordered for a smartphone with high output impedance or just generally lazy sound quality. We'll see.
Impulse's picture

Looks kinda pricey compared to some of Sony's BT receivers with comparable battery life AND a display for track info, caller ID, etc... But if the sound quality is a cut above the rest it might very well be worth a look.

I'm definitely looking forward to your take on it. I don't particularly need the display on my Sony anymore since my smart watch accomplishes the same function. Being BT 4.0 that Noble unit might get better battery life than advertised with BT4.0 compatible phones.

I've heard great AptX BT devices as well as awful ones, not putting much stock that, the standard SBC codec seems decent enough if a device uses the highest bitrate... I've wondered whether AptX is more efficient but, no one tests for that kinda thing.

John Grandberg's picture

We'll see. The sub-1 ohm output impedance is promising. You don't typically see that spec on gear from other brands.

Which Sony model do you use?

Impulse's picture

I'm using a Sony MW600, pretty old unit, I think it's discontinued now but still widely available at close to it's original price. I believe they replaced it with the MW1 but that seems discounted too, not sure if the SBH5x models are their most current or what.

I get pretty good battery life out of it tho (over 7hrs still after a few years), I remember comparing it to my Clip Zip with my Ety hf3 but it's been a while... Now I'm curious to do so again.

Ended up settling on it basically based off Amazon reviews, a couple positive comments about it or the MW1 on Head-Fi, and just the fact that it looked better than a similar unit by LG. It's hard to find detailed specs like output impedance or DAC used, much less anyone that has more than one of these things for comparative purposes.

ManiaC's picture

Please if you can add Cayin N6 and Fiio X3 2-nd generation.

John Grandberg's picture
I have the Cayin N6 here now, as well as QLS QA360. Both are worth talking about. Should be able to get the Consonance Suzanne as well, but I'm not sure if the Questyle QP1 will be done in time.
Tyll Hertsens's picture
Yeah, but by the time the Questyle comes out you'll have a lot of great experience to evaluate it with. Thanks, John, great work here.
tony's picture

Another Wiki type of reference work.

You guys keep hitting home runs.

This portable comparison is doing Tons of work for me and probably for everyone else.

I'd buy a plane ticket to see a Seminar with all four of you lads.

You 4 are becoming a "Top Gear" type of experience, you might be able to do a weekly show ( remote kind of thing, like that TV guy does ). Betcha you'd be getting a huge following.

Tony in Michigan

elfary's picture

iPhone 6 output impedance is 2.3 ohms. Check your facts (or measurements).

tony's picture

Nice catch here elfary,

Tony in Michigan

John Grandberg's picture
And so did Ken Rockwell on his site. He got 3.18 ohms on the 6+, and I got a bit higher than that. Within margin of error/unit to unit variability I suppose. The point stands that it's pretty good as-is, but not perfect - there is some improvement to be found with a lower output impedance, when using certain IEMs.
Stefraki's picture

Have been increasingly falling in love with my Pono. Functionally speaking, it's very silly in several aspects... sound quality-to-price ratio? It's amazing.

John Grandberg's picture
Pono will be included in Part 2.
ednaz's picture

It's difficult in these online shopping days to do good research on your own. When I decided I wanted to step up from the iDevices, I couldn't find anyplace where I could listen to 2 or 3 alternatives with the IEMs and headphones I own. As fraught with argument as an exercise like this can be, it's a necessary tool (unless someone wants to order four or five units and sell off the ones they don't like.)

I agree on your assessment of the Fiio X5 sound, that's agreement from someone who enjoys listening to the device. But I think it's a problem with some earphones, but not at all with others. With my Westone ES5, it's edgy metallic for sure. But with other earphones or headphones - Xiaomi Piston 2, Ety custom sleeved, ACS T1 CIEMs, my AKG Quincy Jones portable headphones - it's not noticeable at all.

That's where the YMMV comes in - really seems to me that in a lot of cases you need to look at DAP/headphone combinations. Which makes for a combinatorial nightmare. Still, with good roundup reviews like this, and knowledge of your own headphones, it's possible to get to happy.

Three Toes of Fury's picture

I absolutely enjoyed this first collective look at DAPs.
Thank you very much John for compiling your thoughts and sharing them with the innerfidelity gang.

I share @ManiaC's interest in the Fiio X3ii as its been getting some pretty great buzz on other audio sites. However im guessing its sound quality wouldnt exceed the X5 and we have your review for that one.

Keep up the great work and keep sharing your thoughts and reviews. We headphone fans love our electronic toys..having more DAP reviews and wall-o-fame entries are a perfect fit for this site!

Peace .n. Living in Stereo


PS: What about adding Zunes, Archos Jukeboxes, Creative NOMADs, Diamond Rios, or the audiophile-standard-setting coby usb player!?

tnelson's picture

I'd be interested to know more about the target users of dedicated DAPs with higher SQ than iPhones and other smartphones. I honestly am curious about this issue…I understand wanting the best possible source for an environment in which you can discern SQ clearly and maybe wanting a physically small personal source that can be moved from quiet listening site to site (home, office, etc).

However, I am skeptical that benefits of a high-SQ DAP can be heard if used as a portable player. On streets, planes, cars, in coffee shops…there's no way I'd be able to hear an enhancement beyond my iPhone, regardless of how good the source or IEMs. Too much isolation or noise-cancellation can be dangerous on the street, so there's always going to be ambient noise.

I would still need my phone for streaming (or lossless downloaded) TIDAL, internet radio, plus all the non-audio smartphone functions. Why carry another device? It would be interesting to evaluate a current iPhone and Android phone among the DAPs being compared for SQ, for folks like me who are skeptical about the audible benefits of carrying a second audio device. Doesn't fit my lifestyle, but what is the target listening market for these?

John Grandberg's picture
I definitely agree that any benefit is lost in a noisy environment. That almost goes without saying. But each situation is different - two people commuting to work might have vastly different ambient noise situations. One might not be a good candidate for anything beyond a phone and decent IEMs, the other might be well served by a nice DAP and higher-end IEM. So you have to examine your own scenario and go from there.
On Song Audio's picture

Hi I am the U.S. representative for the M. Please keep in mind that the M can play while plugged into a 5 volt USB supply. The 4 to 5 hour battery life applies when a power outlet is not within reach.

Laistrogian's picture

I'm wondering if it's possible to do measurement for these DAPs. While I can understand why some people would want to by DAPs, something like A&K240 comes across me as being "unnecessary."

You could call me objectivist or something like that but for me it's still physics, if the numbers are the same they should sound the same.

SixChannel's picture

2 years ago I settled on a Samsung Galaxy because it 1)has a true FM radio, 2)has open architecture for music player and 3)allows me to peruse the innumerable internet stations. Although I see FM a lesser draw these days, opening up to the internet swung the deal for me. The only unfortunate part is that the amplifying stage isn't the best for my big cans, but I fixed it by strapping it to an amp.