Calyx Audio M

About myself

I'm 38, so my hearing is possibly not the same as in my 20s. I like various music genres, mainly prog rock/metal, blues and some classical music. I'm not into rap/hiphop/EDM so I don't have a strong preference regarding excessive bass quantity.

Some background

I've purchased this item myself, it was new. I have no affiliation with the manufacturer nor was this a sponsored review of part of a loan tour.

Design and build

This is one of the major selling points, it looks wonderful. Really nice design. Even the USB cables match the unique brown color of the DAP.



Sound

When I purchased this in 2015, it was one of the best DAPs out there. The specification is still pretty good (THD etc.) these days.

Bass is clean but a bit lean. Quantity wise I think it is a bit low, and I'm not a basshead...

Mids are really transparent, clean and also engaging. I like it very much. Vocals sound great.

Treble is delicate, airy and well extended. Never harsh or sibilant.

Output power is not bad, but you'l have trouble driving demanding headphones.



Usability

Here I had many issues. The UI is very slow, not too intuitive and sometimes it crashes. Battery life is below average, not suitable for an intercontinental flight

This DAP was designed many years ago, so don't expect any wireless features. No streaming, wifi, Bluetooth whatsoever.



Comparisons

I could compare it shortly to an AK100 back in 2015 and found the Calyx M better. Since then I have used a Tempotec Sonata HD Pro, which I found better (better bass and transparency) at a much lower price.

Against the E1DA 9038D, the Calyx M has no chance. No contest.



Conclusion

It is hard for me to list so many negative things about a DAP that I used for five years. However the fact is that this DAP was exceptional in 2015, but not good enough in 2020. I loved it but had to move on.

YES!

Yes to this DAP. Yes to how it plays back my tracks. Yes to the shortcomings of the M. The rest is not that important, at least for me. It still might be for you after you have read what follows. This actually is the reason why I am writing these words. To share 100% biased insights about a device that has been dividing people since 2014… and the story continues.



The Calyx M is bringing me closer to the music since two years now. Coming from a 2-way speakers mid-end system and later from a high-end desktop set-up, the Calyx M is, along with the Dethonray DTR1, the only device that did not make me regretting « downscaling » my audio set-up. I still possess a turntable, two CD-Players of choice and a good amp for special listening sessions, but my portable rigs are showing such great synergies, that I really don’t need anything else in my « music lover » journey, at least for the moment. The Dethonray HA-2, the Romi BX-1 and the Phatlab Chimera are most than welcomed companions along this road. Especially the HA-2 in this case, which slightly improves clarity and gives a bit more spice to the silky sound of the standalone M. Still, I won’t consider them within this impression report. It’s important for me to take on the Calyx M as a standalone audio device for this exercise. I have the firmware 1.01 installed.

We like giving marks, don’t we? I am the first, to be honest. It helps categorizing and classifying things we like, but also the ones we dislike. Anyway, why do I give the Calyx M five stars? Firstly because giving less than that would be dishonest. Dishonest, because I have been spending so much time with the M and feeling such an enjoyment listening to my music with it, that it would be really harsh not giving it the maximal score. Then, the build. Hey guys and girls, hold the Calyx M in your hands, more so with the X-Batt module, and you will « feel » quality, the perfect finish and the proud behind producing such a device, meant to pass the test of time. Quality control is not an issue with the M. Why? Because I have three of them…or because I have been lucky. My two spare units are as new as it gets and unplayed, but I have checked them upon receipt and all units were flawless. Get your SD-Card ready from now on.

HONEY
Please find below a non-exhaustive list of the music I listen to :

• Alpha Blondy / Masada (African pop)
• Dykehouse / Midrange (Instrumental pop/rock)
• Thomas Köner / La Barca (Ambient, Field recordings)
• Alva Noto / Xerrox vol. 1 - 4 (Electronic)
• The Sight Below / It All Falls Apart (Electronic)
• Yagya / Rigning (Dub Techno)
• Massive Attack / Blue Lines, Protection & Mezzanine (Trip-Hop)
• Dire Straits / On Every Street (Pop/Rock)
• Roxy Music / Avalon (Pop/Rock)
• Simple Minds / Best Of (Pop/Rock)
• Pink Floyd / The Later Years Box (Pink Floyd)
• Kate Bush / Hounds Of Love (Female Vocalist)
• Jono McCleery / Pagodes (Male Vocalist)
• Johnny Cash / The Legend (Johnny is one of a kind)
• …and Leonard Cohen, Sting, Dead Can Dance, Aidan Baker, Silver Firs, Ramona Falls, Interpol, Kraftwerk, Simply Red, Omar-S, UB40, King Creosote, Boards of Canada, The Black Dog, Phil Collins, Aaron Neville, Björk, REM, Fever Ray, Aphex Twin, Manu Katché + French artists and some OST (Blade Runner, Interstellar, Inception, Hannibal, Twin Peaks)

Please also check my Bandcamp profile, because a significant part of my Electronic music library can be heard on this platform.

FRIENDLY REMINDER
Sometimes, but not always, close your eyes while listening to your music. Do it for an uninterrupted period of 15/20 minutes, it’s enough time for your other senses to decrease in intensity and recalibrating your brain on what you are focusing on. You will get into the music…for real. I am quite certain that the majority of you have done that already, but it is not useless to mention it once again.

THE CALYX M - AN UNCOMMON DAP
The Calyx M is a warm and powerful sounding player, which handles low impedance IEMs and headphones with an iron fist while giving them the right amount of energy and juice but without overpowering them. Only significant power hungry full-sized headphones (300ohms and above) might require external amping via the HO, which is not a LO, but does the job perfectly nevertheless. Thanks to my Head-Fi mate @noplsestar, who told me not to be worried about double-amping via HO. He was right. How much power is needed depends on everyone’s taste and also self-resistance to loudness. I think I belong to the above-average category when it comes to volume. It is unfortunate for the most important component from the whole audio chain, namely my ears, but I cannot be helped anymore.

The ES9018 DAC Chip is implemented with Maestria and is the core of the player along with its Class A amplification section. No balanced output for your headphones or dedicated LO as stated above, but you don’t need 2.5mm or 4.4mm with the Calyx M. You get clear and powerful sound out of the 3.5mm HO.

Visually appealing with its elegant brown color and its big OLED screen, the M is a looker and feels premium to the touch. On the right side, there is a slider which allows a fine-tuning of the volume. I am really digging this.

The UI is a bit laggy, yes. The M is a player that requires patience. Patience by powering it up, by foldering your tracks and also when comes the time to charge it again. One can live very happy with the M without the X-Batt module. You get 4-5 hours of music and then it’s over. The X-Batt gives you extra 1.5-2 hours. Depending on your daily usage, it might be important. It is for me.

Finally, the Calyx M is a DAP that has been produced with an unique prerogative: sound. Unlike the vast majority of the current DAPs that offer lots of features, hence their higher price sometimes, which is to a certain extent understandable, the Calyx M only will playback the tracks from your SD-Card. Forget about the rest, Calyx M is the best. Quite a slogan, isn’t it? No, the reality is different. The M will only please a certain audience and a particular kind of people. A minority actually. Don’t touch this device, if you cannot cope with the shortcomings mentioned in the « cons » section or later on in this article. Waste of time and money. Are you still here? Ok, now that I really have picked up your interest, let’s move forward with a comparison.

A TABLE S’IL VOUS PLAÎT - (Calyx M vs. Dethonray DTR1 - w/o external amping)
Who likes food? I do. A lot, especially Swiss Cheese Fondue (yes, I am Swiss). If I was financially and technically able to produce my own device, I would call it SCF. Joke aside, how can we compare these two DAPs, which only have the same philosophy in the background, but a complete different execution and sound signature following both companies’s prerogatives? Well, food seems not bad to me actually. Let me think about it… Oh, I have something! The Calyx M might be a plate of Spaghetti Carbonara (Roman recipe of course, without cream and bacon, but with the exact portion of black pepper, eggs, pecorino and guanciale). Delizioso. I will prevent myself discussing about the wine in that case, the comment section might derail badly. The Dethonray DTR1, mmhhhh, I see it as a carefully-yet-on-the-rush prepared spicy beef/vegetable wok dish in a small open-air joint in Bangkok (memories got me now…). It starts with the vision of the ingredients carefully chosen and now presented in front of the cook. Then, the smell. Uncooked and later while being prepared. Do you see how the smoke is emerging out of the wok? Do you hear the oil sizzling? The Chef is mixing the flavors, modern alchemy’s happening! The taste and the hearing, two senses that have a lot in common, hence the analogy. We leave the table now and we are going to the salon, where fine spirits and/or coffee with cigars will be served, so that the topic of the day can be debated as it deserves to be. Everybody’s welcome.

Instead of confrontation, I prefer to talk about two devices that complement themselves in near perfection. No deathmatch here. If you have access to Internet, you will be able to get information about the technical datas and the features of both DAPs. As you might have understood, I will pass on the technical « blabliblabla » and go right to the point: sound, and later on, synergy.

The DTR1 is the anti-doppelgänger of the Calyx M. Or the opposite…if you prefer. No touch screen, almost 3x lighter than the M, much smaller housing and tiny display. Holding both devices in your hands is something. David vs. Goliath? At first sight maybe, but the DTR1 might have a winning hand. Beware its low-profile, it’s the devil in disguise. It starts with a dedicated LO, and not the worst one. Anson Tse, CEO and founder of Dethonray, used to work for Hifiman, Sony and other brands as an engineer. No need to tell his story one more time here. Check by yourself on HF or on the www, but Anson knows how important the power stage is and the difference it makes at the end of the day. Clear and powerful sound, impressive detail retrieval, pretty silent, it hisses sometimes with BA-only IEMs, though. Choose your drivers wisely (or add a good amp to reduce the hiss). With hybrids or single DD, you should be fine. It continues with its real portable size. Take it with you everywhere. Yes, why not? The DTR1 embodies portability. Solid and compact, even more so with its cobalt blue suede protecting case. My favorite IEMs with the standalone DTR1 are the Sony XBA-N3 and the Etymotic ER2XR. The N3 finds its better half with the DTR1, even in a 3.5mm connection with the Sony MUC-M12SM2 cable. Warmth, slightly boosted bass, balanced mids and tamed treble. Perfect combo for the office. The Ety also offers great synergy with the DTR1. Lighter than the N3, the signature gains in resolution and speed. It’s immediately noticeable. This pairing is perfect for the office in terms of isolation and sound.

WEAPONS OF CHOICE



The P-EAR-S UT-3 is a semi-custom tuned 3BA CIEM. Among the IEMs I own, tried or got on loan, this is the earphone which matches the Calyx M at best. The DTR1 and the M were my sources while tuning the UT-3, so it’s logical that one of these DAPs was meant to be the right partner at the end. The DTR1 brings a slight hiss into play, nothing bad, but such a specific tuning finds its best partner in the Calyx M, more so with the Romi Audio BX-1, which annihilates noise floor completetly. The UT-3 is a slightly midbass friendly version of the SH-3 from P-EAR-S Audio. Check HF for more information about this Swiss-made IEM, which deserves much more attention as it gets today. Otherwise, the Sony N3 via the Romi BX-1 or Dethonray HA-2 amps also is a nice sounding IEM out of the M. What about the Final E5000? Well, I love it right out the DTR1/Chimera combo, but not with the Calyx M. Overdosis of sugar and honey. The Etymotic ER2XR once more doesn’t fail and sees its DNA being brought to the next level. A punchy yet controlled bass, beautiful transparent mids and pleasing highs. Great combo indeed.

ACCIDENT IN PARADISE
The sky is not always as blue as one might think. The Calyx M is not a perfect device. It’s not meant to be. As stated before, there are shortcomings which cannot be ignored. UI, battery life, sudden app crashes, etc… I am not trying to « defend » an electronic device for its flaws, but these don’t matter to me. At all.

AND NOW?
Now? Well, I don’t know. Get one maybe and try it by yourself. You might fall in love with this particular and unique sound signature. If you do, the shortcomings of the M will be forgotten or, in the worst case, forgiven. If you don’t like what you hear, there are other options available, i.e. the Dethonray DTR1, or any Cowon DAPs that use the Burr-Brown DAC-Chip.

REQUIEM FOR A DREAM
Knock Knock Calyx! Are you there? Fairytale time down here! Please tell us a bedtime story. Should I start? Once upon a time, a company that vanished too soon decided to revive from its ashes and engineered the Calyx N. Not the M2 or the M Pro. N because of a New start. We wait and we wonder, as Phil Collins sang in 1992. I will do it myself, even if it takes years. There’s nothing like hope. Meanwhile, I will keep listening to your best offering so far, the Calyx M. Thanks for everything Calyx, you’ve nailed it right from the start.

AFTERPARTY
Let’s end all this with seven pieces of music I like to listen to with the Calyx M and while writing the above. It’s quite a moody tracklist, but it’s nice music anyway. Why seven? Because this is my lucky number. Maybe it’s yours as well?

Press. Play. Button.

Having listened to almost all top tier DAPs, the Calyx M has been frustrating to audition being relatively rare and absent from all audio shows and Head-Fi meets in the US that I have attended. Hearing/reading constant claims of top SQ, I knew that I needed to hear it, but doubted that it could be that good knowing that it utilizes a Sabre implementation which are bright and blaring in practice. With the prices coming down to a reasonable level, I took a chance on buying one to audition knowing that I would just sell it after my audition satisfied my curiosity. Well........ a week into my audition and I knew that there was no way that I would be selling the M. It just sounds too damn good!!!
 

The BAD

Lets get this out of the way - there are 3 reason to never touch this DAP if you care about anything but SQ. My listening is typically random songs within a play list folder or just random listening through all music in my library with my eyes closed, the screen off, and a finger on the forward button. The M fights me tooth and nail on my listening style requiring huge amounts of effort to just listen to my music. Given the issues I almost gave up in the first week. Also, at first, I was not impressed with the SQ as I was too concerned about fighting the UI. I also needed to learn to turn down the volume to eliminate the Sabre blair as the volume is not needed like on most DAPs to be full sized and dynamic. It took me a bit to dial in my listening sessions to find the value as the rest just pissed me off. So here are the main three reasons not to buy this DAP:

• Useless Battery Life: At less than 4 hours, the M doesn't even last my night time listening session without help. As such, I just keep it plugged into the wall with a long cord. The good news is that it seems to sound even more dynamic plugged in so I have overlooked this issue. I also have a USB battery pack that I can utilize, but that gets heavy and cumbersome - prefer the wall plug for my purposes.
• No Folder Browsing: My MicroSD cards are mirrors of my playlists to allow me to play my folders like playlists without having to mess with the UI. Trying lots of DAPs, this has always been the easy work around to less than optimal UIs. But the Calyx M has no folder browsing option making this setup inoperable. How can any DAP not have folder browsing, that is just a basic requirement and a starting point for creating a UI. Even worse, the Calyx scans the cards every time it is started to rebuild the library taking additional time to start functioning.
• No Play All: Ok, at least I have access to my music through my library. Or do I........ Turns out that the Calyx M will only play one song at a time. Choose any song through the songs list or by searching and it will play that song and stop. If you choose an album it will play those songs as a playlist, but that hardly supports my goal of random playing of various artists. Even worse, without access to my folders, I cannot see what is in my playlist folders to build my playlist requiring me to go to a computer to look it up. To listen in the fashion I like, this means I have to use the Calyx UI to build a play list one at a time which would take hours to replicate. It also has something called a jukebox that I can add all my library to one at a time which will finally allow me to play all songs randomly. Out of frustration, that is the course I chose and it took me three days of several hours a day to complete. Since I cannot see my folders, I will still be in trouble if I try to add music to my library in getting them into the jukebox as I will have to make a list of those songs and use the search function to find them one at a time to add. What a major pain in the ASS!!!!

 

The GOOD

Was it worth the hassle, YES!!! The SQ is very addictive, but I will get into that later. The DAP itself stands out vs. other DAPs in its design. Here are three reasons to love the Calyx M in addition to its awesome SQ:

• Amp: No need for a stack with this puppy, the SQ rocks my HifiMan HEX without any need for an amp. This claim can only be made by the Paw Gold and the Sony WM1a/z and maybe the QP1R if you like its signature. This is a major accomplishment to have a desktop level experience in a DAP without the extra clutter.
• Build: The Calyx M is a work of art that stands out as richer looking than the other DAPs on the market. While AK is the top dog in this area, they are different, but not better than the Calyx M build. Many might think that the M is the more expensive device when side by side with the AK lineup. The brown copper color is beautiful and rich looking without being flashy. The M is heavy and stout feeling for its size giving off the feeling of quality vs. the standard cheap, light, and flimsy we are accustomed to elsewhere - sorry Aune M2. The M is smaller than I thought it would be based on other reviews and is very comfortable in the hand. The rounded corners are nice to the touch.
• Storage: This DAP sports 64GB internally and provide both a full SD and MicroSD card slot. That means we can have 800GB or so for a library. While my library is well over a TB, most is junk with all of my playlists coming in under well under the 800GB capacity. 
• Screen: The M has a very nice screen that stands out as unique in quality and UI color popping. This adds to the overall look of the build and plays well with the brown copper coloring. The M has the most usable screen that I have seen to date with the exception of the new Sony WM1a/z.
• UI: While not perfect and requires a little attention at first to use, the UI is very easy to navigate and very colorful adding to the experience. Forgetting its weaknesses mentioned above, the M is as nice as the AK and the Sony UI which is saying a lot.

 

The Sound Quality

This is why I am not selling the M. It is like no other in its abilities/signature making it a keeper even when I get my Sony WM1A. My AK100ii will not be so lucky as it is easily outclassed by the Sony. So here are the key factors that define the Calyx M sound:

1. Black, Black, Black Background: The first comment I get from other listeners is how black the background is. It is so black that it is almost jarring. Starting a song feels like a failure until the music starts playing. Pauses sometimes sound as if the music stopped. Space between instruments are large voids of emptiness. I have never heard such a blackness in the background before, even on the highest end desktop setup that I have had the privilege to listen. This is the most unique feature of the SQ which enhances the rest of the value points. The details that pop on the M would be covered up without this blackness to frame them. The dynamics would be muted without the blackness from which they start.
2. Dynamics: This is another unique feature of the M that stands out. Big sound seems to come out of nowhere without warning. Most DAPs severely smear their dynamics where the M seems to have micro-dynamics individually with each instrument. Rather than a big increase in sound at a loud passage, you can hear the different levels of loudness/dynamics of each instrument and the boom seems to have space between. This is a very different experience that allows deep bass to boom while maintaining the delicacy of the symbols and its shimmer at the same time.
3. That Boom you Feel: While I wouldn't classify the M as a warm DAP, it is a warm DAP on a warm song and that bass goes booooooooom! The bass is detailed and delicate and deep and does not step at all on the mids. Even the symbols can have meat on them when called for. The blackness allows this by providing space between instruments. However, it is not all about the boom, it is the timbre and the texturing that comes through and gives you the shivers. A piano sounds like a piano and a bass guitar sounds like a bass guitar. You can feel the texture in the strings and feel the pluck. This is what draws you into the music and brings tears to your eyes.
4. Full Sized: Another unique aspect of the M is the full sized sound which is properly scaled and lifelike. The band sounds like they are in the room with you surrounding you with sound. This is not to say that the sound stage is small, this is to say that you are on the stage with the band with all the detail in your face. But this is a good sized stage that you have to walk around, not shoulder to shoulder. When the singer sings, they sound human, not tiny and distant. You can hear the breath and feel the emotional connection. I have only experienced this on total desktop setups before.
5. Voices: Voices both male and female are stand outs on the M. Whatever voodoo magic they are using, the voices are always forward on this device and singing directly to you. The voice timbre is excellent and really pushes deep detail.
6. Detailed: The blackness gets the song out of the way of the delicate details. The detail I hear is immense. Even the symbols have character. So given the blackness, the dynamics, the texturing and timbre, and full sized presentation, the result is a stunning natural sound. Yes, I am hearing things I have not heard before... blah, blah, blah - but also in a way I have not heard before. There may be some trick to the signature that makes these familiar songs feel different, but it is very much like listening to them for the first time again. This is what is so addictive.

 

DAP Comparison

If you cannot tell yet, I am digging this SQ. But how does it compare to all the others? Here is my opinion:
 
Sony WM1A/Z >= Paw Gold >= Calyx M > Aune M2 >>> AK380 > AK240/120 > AK100ii >= X7 >> Lower Tier including X5, DX90, QP1R, etc, etc.....
 
The AK380 scores low because of its extreme need for an external amp. It couldn't even run my CIEM properly without one. With an amp, it rises to the level of a $350 Aune M2 in SQ. However, the AK380 looks make my heart go pitter patter.
 
Now my disclaimer, please keep in mind that I do not have all these DAPs sitting in front of me to compare side by side. I am working off my memory and some detailed notes. I should also point out that these DAPs were often listened to in RMAF type environments which are less than ideal and for a limited time. Firmware may have improved these DAPs SQ as well. So feel free to ignore my opinion - it is just for fun.
 

Headphones Pairing

I am still early in my review cycle and have only used my HEX, the LCD2, and HD700. While they all sound great, the HEX is a match made in heaven so I have just used it in awe. When my CIEMs get back from Hidition, I will update.
 

Conclusion

The issues with this DAP are horrendous. However, if you can hold your nose and work through the issues as I have your are rewarded with liquid gold SQ. To me it is worth the effort.
 
Now that the price has fallen to sub $500 used, it is a screaming deal. If only Calyx would update the UI for my two complaints, I would be a happy man and can live with the remaining battery issue. If Calyx can accomplish this SQ with a horrible Sabre chip, I can only imagine what they could do with my favorite AK4490 chip like in the AK380 or the Aune M2. Calyx... we are waiting!!!

 
Thanks to Calyx for allowing Team Tokyo to borrow a unit for review.
 
Note: Version 0.6 and 0.95 of the software were originally used for this review. I've updated it to reflect performance with firmware 1.01.

The first thing many people wanted when they heard about the Calyx M was an AK240-level device without the price tag. Good luck! But in all honesty, if there is another company (other than Sony) that might be capable of invading the market with something competent, it would be another Korean company. Having owned a Calyx DAC in the past, the DAC 24/192, I was curious to find out how their portable would fare, so when the CEO of Calyx introduced himself at the May 2014 headphone festival in Tokyo, I didn’t hesitate to ask for a loaner unit.

The first physical impressions I had of the unit is that it is big, relative to the other DACs I have on hand. If you saw the photos of each individually it is natural to assume that the AK240 is the largest, when it is actually the smallest overall, if a bit thicker than the M.  Other than the very straight-forward design of the M compared to the X5 and AK240, the two most noticeable physical details that set themselves apart from the competition become quickly apparent on picking it up: The two memory card slots: one microSD and one SD, and the magnetic volume control. If you’re wondering whether you can take the volume control off, the answer is: Yes, you can. But the magnets are strong enough that if nobody had told you about the volume control being magnetic you probably wouldn’t notice, as it is almost as difficult to remove as a non-screw-tightened volume knob would be.

The large screen is filled with an equally large, easy to read and beautiful Android-based custom user interface, which one navigates primarily by swiping left or write to get to the music and Jukebox feature respectively. Menus at the top access information and settings for one, and the currently selected album or playlist on the other. Centrally, of course, is a playback screen with the play/pause control overlaying the album art and quick access to repeat and shuffle available, along with track information.  This makes the Calyx M’s user interface very quick to pick up and use.

The lock screen, which uses album art as the control to unlock it can be disabled in the settings, allowing the power button to switch on the screen and take one straight to the music playback controls.

At present the user interface stutters a little when swiping quickly, and quite severely lags during music playback if you try and swipe quickly. Card scanning can take a few minutes if you have a lot of music, but Calyx have been working steadily on not only improving the performance but adding features such as search. Features such as easy re-ordering of songs and the Jukebox feature are good with most controls large and easy to tap. However, the lack of folder browsing ability may be a show-stopper for some.  Indeed it was a problem for me, as I have a separate folder of DSD files that I usually access but can't easily on the M.

Tapping and holding on a track, for example, brings up the options to get info, add it to the Jukebox or to a playlist or delete, for example, which is very handy. Likewise, Jukebox songs can be selected individually or in groups and new playlists created.  Shifting off the necessity of creating playlists on my computer is definitely a bonus for me.
 
For different types of headphones, 3 different "Impedance Matching" settings, labelled "Low", "Mid" and "High" are included which change the volume profile. This has confused some people into thinking that they change the output impedance of the player and will sound different when all they are doing is adjusting the volume.

The main troublesome aspects of the user interface is that it badly needs an album art cache, as the album art has to be loaded from scratch every time the unit is switched on, though it doesn't take nearly as long as it did before 1.01. During very vigorous scrolling while playing back high-res music, I did manage to get the music to skip. There have also been complaints from users about battery life only lasting 4-5 hours of playback (3.5 hours with DSD and the screen off). However, Calyx are working steadily on improving the software, so I’d expect in time things to get better.

Sound-wise too, the performance is very good, if a bit behind the AK240 and seems to be a bit “darker” in presentation. Music comes through cleanly with a wide soundstage whether using IEMs or full-sized headphones, for which the Calyx M is more than capable of driving. The Calyx M with the HD-800 and Audeze LCD-X, while not driving them with the authority of a desktop amp still managed to do a good job with the sound, the main thing lacking was volume level on the tracks from David Chesky’s Open Your Ears album. The gain level was far better suited to IEMs. However, gain settings exist in the settings under “Impedance matching”. With version 0.95 of the software, putting the M on the highest setting improved the performance with the HD-800s compared to version 0.6.
 
At the request of some Head-Fiers, I compared the sound to my iPhone 5. Both with IEMs and full-sized headphones there was a distinct jump in both clarity and headphone drive with high-quality music. Compared to the AK240, the latter had the edge on detail, but to use the words of a fellow member, the Calyx sounds more "full-bodied" and was a better match with less bass-strong headphones. The M was a touch less smooth in the treble compared to the AK240 -- only in comparison however. I'm not sure if this might disappear with use as I've experience with other equipment that was new when I first received it. Using the single-ended output on the AK240 and firmware 1.01 on the Calyx it was very hard to make out any difference. 
 
The biggest difference was going from the X5 to the Calyx with full-sized headphones. The X5 is very poor with high-impedance headphones at producing a wide stereo image, being far better suited to IEM usage. Going from there to other DAPs I feel the differences come down more to sonic preferences and features desired, as the Calyx doesn't have optical output, a dock, wireless update and streaming for example, nor as much internal storage as the AK240. Going a bit sideways in comparisons, the M sounds a bit more spacious, though not as "meaty" as the Aurender Flow. That makes me prefer the M, though at least one person I know feels the other way around.

The Calyx M can also be used as a DAC, though I did find the sound quality to be somewhat flatter-sounding and dull compared to using it as a DAP, with better USB cables and high quality external USB power improving things. Since USB isolators are quite inexpensive nowadays (eg: The Schiit Wyrd) the Calyx M can be readily used as a high-quality DAC or pseudo desktop solution.

Overall the main thing is that the Calyx M will be giving the iBasso DX100, AK100II and AK120II a good run for their money, if not quite, in my opinion, the AK240 (at least not on features). I do think in a year, if they keep up the steady improvements to the software, they’ll gain a lot of fans.