April Music Eximus DP1 and S1 review test

New April wind

April Music Eximus S1 and DP1 are for sure an interesting package. Dmitry from Transparent Acoustic insisted, that I should try them together and so they arrived as performing partners.


Alex Rasmussen of A-Rex/Neal Feay designed the chassis cosmetics. He owns a full-capacity machine shop in Santa Barbara, CA and is famous for his remarkable industrial designs for Ayre, Constellation Audio, Resolution Audio and many others. The basic design concept of the chassis is the leaf. It represents springtime and with it the month of April like company name. The volume control, engraved details on the top and all the lines are based on this leaf theme.

Class D

April Music Eximus S1 monoblocks under review are the latest upgraded version. This version adds much improvement to the power supply section and consequently to performance without raising the price. Thumbs up.

With the rise of Class D in past few years many companies jumped at the implementation of this technology. I heard few examples of first commercial products almost decade if not more ago and it seems that refinement finanaly came after a long way. I'm not saying it reaches its peak yet, but we've seen many audiophiles and music lovers fund their peace with this type-class of technology. Vinyl for example or analog took how many years to excel? I guess something worth mentioning.

So did Class D managed to rival Class A and Class B? From the sound approach there are still things to hanker about. When we address the practicality, low consumption, greener then green approach, small size, great efficiency, almost no thermal impact and great power for the given size it can be understood why many companies took that route. Jeff Rowland jumped the wagon long time ago, Mark Levinson top range monoblocks use Class D and non-the less highly acclaimed Devialet hybrid approach look at it with unique implementation. Some says old Quad idea packed into the new clothes makes Devialet nothing special, yet anyone who tried it, including me, falls its for the integration of technology. Bang and Olufsen never hides the roots of their technology and their OEM ICEpower modules are widely used in vast applications. From car industry, portable players, consumer electronics to high-end audio.

So why this short elaboration? I feel strong that Class D amplifiers came to the level of industry usage, that we cannot ignore it anymore. Like it or not, any serious audio reviewer needs to at least keep an open mind and stay up to date with the current movements of a technology trend that already grew beyond niche market appeal.

We live in 21st century and things tend to get smaller and slicker. Not to forget easy to use and being practical. Class D modules opened up the whole new range of products, which suddenly takes much less space and emits far less heat. Everything could finally shrink down and starting to integrate much more into the living environments of both audiophiles and music lovers.

I'll try to avoid negativity often instantly related to Class D amplifiers among audiophiles. As with mp3 it brings something larger to the table. Yes, I'm sure we all know shortcomings of both mp3 as medium and class D as amplifier technology. In the roots they’re both dealing with the matter of ultimate sound quality. Everything works within dualism in this material world and ying-yang observation might be an eye opener for hard-core audio fundamentalist. Both technologies mentioned opened up doors to larger audience. Those two might have their side (d)effects we would like never to apper, yet eventually some of that crowd using them will move along and evolve to more sophisticated listener wanting better more capable system and higher resolution. Yes it can be double-edged sword. But!... Give people choices, especially in shops or distributors demo salons where people can experience and hear the difference. Gradually and eventually they’ll move up on the ladder of quality. Some for sure.

Let me sum up and try to address Eximus S1 mono-blocks strong points. They're small, stylish, in absence of heat, easy to integrate and most simple to use. I don't see only entry-level music lovers or audiophiles being thrilled by them. Eximus S1’s brings the audio technology in an uncluttered way and as a true no brainer. I've seen many long time audiophiles living the "traditional" Classes for this efficient one. Why? At the end of the day many of them simply wants to enjoy music without thinking always what to add, subtract, which cables to use etc.

From what I've heard in Class D so far in many different applications one thing that continually stood out was a consistency in sound. This might not be your ultimate quest for audio revelation, but all music plays in a similar way (listenable) yet still recognizing way.

Should this be called colored or artificial consistency? Perhaps. As said and written before at the end of the day its up to the people choices what and how certain product is or should be used. If that makes them happy and bring closer to the music who am I or we to judge.

April Music Eximus DP1 

The EXIMUS DP1 is a high-end digital to analog converter up to 192kHz/24Bit, which can also be used as a pure preamplifier and top-quality headphone amplifier. The DP1 has 6 digital inputs including USB 2.0. Each input supports playback of files up to 192kHz/24Bit (44.1, 48, 88.2, 96, 176.4, 192kHz). For USB this is accomplished with the ultimate USB 2.0 solution from XMOS with its super-quality oscillators (2 separate oscillators for the multiples of 44.1 and 48kHz).

All six digital input converts via a pair of PCM1794A DAC chips. They work in a true dual mono mode. Asynchronous USB Class 2.0 input seems mandatory these days and you’ll find also two S/PDIF digital ins, AES/EBU, Toslink optical and a I2S input. I’m seeing I2S on more and more devices and I guess we can expect much more front-end devices with this connection in near future.

Asynchronous USB locked without a problem with my solid state based MacBook Air. Apple OS X needs no additional drivers for 24/176.4 and 24/192 replay, but you’ll need some good program like Decibel, Audirvana plus, Ammara etc. to get the best out of you digital music.

Eximus DP1 natively works with 24-bit at 192kHz. When locked small LED located between the power and sources switches operate in three different colors. Yellow stands for a 44.1/48k signal lock, red for 88.2/96kHz and finally green when a 176.4/192kHz signal is locked.

In the similar ‘fashion’ between the filter and volume button a up-sample button shows the status of operation. Yellow again shows 44.1/48k signal lock, red 88.2/96kHz green 176.4/192kHz and no LED light stands for for a signal pass-thru. For best results, especially when locking into the MAC OS-X exclusive integer mode, this is a way to. My listening notes repeatedly showed this highlight.


April Music Eximus DP-1 is actually three in one device. Preamplifier, headphone amplifier and DAC (digital to analog converter). If we separate each unit and judge it in a sole function you can have all three of them rated as great performers worthy of 3k and above price range. I’ll elaborate more later specifically, but as with Burson Audio Conductor DP-1 brings hell a lot to the table. Both performance and price-wise. Few years back you would have to pay 15k or more for the similar performance in digital audio for far less performance capability. Sometimes we forgot how far digital advanced from its rise in 80’s. As written, my faith in digital is coming back like phoenix bird rising. Do not let get fooled by my love for analogue. I was one of the first adopters of digital when kicked in. From computer music making, PC audio and when CD’s, transports and separated DAC’s kicked in. They sold us a great story of perfect sound forever and ready for masses. What a gimmick. Only now I feel, that digital is evolving into something that I can bare to listen for a longer time without digitalis or strong listening fatigue. Burson Conductor, Lampizator DAC, Aqua Hifi Le Voce DAC, Audiobyte Hydra X interface and Eximus DP-1 are some of the products that bring sophistication of digital into an actual working solution.


It’s hard not to fall for the aesthetics of April Music Eximus DP-1. I love the natural references in high-end audio. Be it Golden Rule (Devine proportions) or the design, that reassemble the natures line; I’m hooked. Eximus DP-1 breaths with fresh and unique design, that simply flows and can stand on it’s own in the surroundings. The leaf motive works seamlessly with brushed aluminum and its compact size saves a lot of space in the featured packed product.

April Music Eximus DP-1 represents a new wave of lifestyle high-end products, which are both feature packed and aesthetically pleasant. I for one do love the “return” of lifestyle trend as it simply the dealings with audio gear and makes operating with high-end gear less erratic and wanted.


You might have some reservation at first contact based on the size of Eximus DP-1. Your mind could go bonkers; “O.K. It looks gorgeous, but how something of great performance can be squeezed of it?”

You couldn’t be more wrong if you judge DP-1 or any gear at present times based on their size. Like with computers and communications devices everything advanced in past decade with power of SMD and electronic minimization. Minimization is not a mandatory call for quality, but with careful selection and audio engineering it can work with great results. Eximus DP-1 is a living working proof of great implementation of skills and audio design. 

Eximus DP-1 goes beyond technical sound like often associated with converters like Weiss. Great sound and pro nature, but for me without the real life. DP-1 has this hard to describe transparent warmness, which resemble natural timbre and character in much more convincing way to me.

Transparency, speed and stability

There is much iteration of DAC implementations in contemporary high-end audio design. You can go NOS and no oversampling route almost unlimited. Those are easier to design and with much more predictable results. When it comes to the usage of modern DAC devices things changes dramatically. Not being careful and skilled will quickly and mandatory result in an open and dynamic, but harsh related digital sound.

April Music Eximus DP-1 is well-balanced device. If I needed to quickly sum its performance then transparency, speed and stability first come to mind. For a change DP-1 works well in the domain of positive transparency. It does not make things sound “edgy” in mandatory way as with many DAC devices priced below and above DP-1. Speed might be the attribute that everybody jumps at when mentioned in high-end audio. Combined with the stability it recreates the embodiment of the “correct” and so-called needed ingredients of high-end audio reproduction.

I actually love and not only like what Eximus DP-1 have to offer. It’s a rare correctness wanted in the performance of modern DAC’s. With many DAC’s you need to start an uncertain quest of compatibility and system integration. I’ll have to say Eximus DP-1 exhibit one of the least complicated ability to integrate without giving much stressed to the endless permutations of cable and component balancing. I’m not saying DP-1 is prone to them, but its inherited transparency open up a window of much less cluttered way of designing and tuning the high-end audio system. Eximus DP-1 is not the last word in digital audio, but it’s very nicely positioned among the competition and acts as solid PCM audio device.

Three in one

I wont go in elaborate state for headphone and preamplifier function as many things are already written about Eximus DP-1 performance. As stated before I boldly declare, that DP-1 can stand on it’s own as a high-performance high quality modern preamplifier. It’s truly balanced and with least possible “flavor” added to the gain structure yet still within the positive darkness of natural sound imprint. I still urge you to try adding separate preamplifier if used as DAC as it open things of performance even further. Used in combination of Robert Koda K-10 preamplifier with balanced connection DP-1 really showed it’s capability to go beyond it’s given price range and most importantly performance. 

With headphone amplifier on board you’re quickly entering the one step solution of instant satisfactory high-end audio reproduction. Adding matching headphone will open up a great universe of high performance headphone listening. Acting as preamplifier and with AUX in you can add turntable and enjoy the reproduction quality that we all hankered few years back in time of head-fi phenomena rise. I cannot repeat myself enough about joy and completeness of great headphone rig. For the third of fifth of the price you’ll get almost the same if sometimes not even better performance of speaker based two-channel system. In absence of problems connected to room acoustics one can really enjoy the ability of DP-1 as balanced and musical hub for your aural enjoyment. Be it as audiophile or music lover. Invest in Sennheiser HD-800 headphones for example and you’re set for a good time. Interestingly, for some it might even be the end of voyage.


Eximus S1 and DP-1 touched a certain soft spot in me. They’re both great looking and compact high-performance devices that can operate without modus operandi. This is something I and I know many of you wants. When combined DP-1 and S1 makes a great sounding combo with as least possible cable clutter and very little physical space taken.

Eximus DP-1 is a compact, greatly designed, well-performed and great sounding product. It’s and audiophile or music love dream come trough. As I said before few years back we would have to pay premium for performance and quality that DP-1 is offering today. Sometimes I ask myself what is an actual high-end device and in many reviews I’m hard press to search for pin down attributes to connect to. With Eximus DP-1 I need no artificial or hard looking anchor points. Eximus DP-1 is a no brainer to recommend and it clearly wins Mono & Stereo value and performance award.

Eximus S1 monoblocks are interesting devices. It’s a bit harder to shoot out and blindly recommend them for an instant audio nirvana as with DP-1. I know for fact that many customers exchanged their bellowed “big boy” brand names amplifiers for Eximus S1 and leave happy ever after with them. So how to wrap things up about S1?

Eximus S1 is system dependable and brings certain performance that in long run even I can see myself living with if not being reviewer (or this might being a good excuse). Heresy? It won’t go as far as great Class A or Class AB amplifiers in it nature, but what Eximus S1 brings is stand out consistency. Here is the key of understanding why S1 works for so many people. One thing I have experienced with all Class D based designs, even with Devialet Premiere is a constant balanced performance. On top of that it brings a revealing act, but somehow not being the main thing of performance, but more side thing. In that way it can be understood as consistent performer across the genres. Isn’t that something worth considering...?

In last minute way and especially in this case thanks God for my stubbornness and persistence I went further. With all combination possible when testing the gear under review sometimes mind got really baffled. People tend to think what a luxury and pleasure is the task of reviewer. You just enjoy the vast number of world-class gear coming in and out frequently and write about them as you feel. Well, in a way that might be true. Anyhow. When actual listening and reviewing taking place there are an endless ways of mixing, matching, elaborating and countless mind contemplations. This takes time and clear focus to stay objective over time and not simply repeat yourself in a parrot ways :).

I’m glad my mind didn’t put me at ease with pair of S1’s. All the time I just couldn't put it to rest repeating to myself, how there must be something more about it. So… I paired Eximus S1 in full balanced and bridge way to what is considered as one of the currently top five preamplifiers in the world, namely Robert Koda Takumi K-10. Now this is 30k GBP device. What in the heaven’s name are you doing in pairing it with Class D? Read on… Going full balanced from Eximus DP-1 to Robert Koda Takumi K-10 and from there to both of Eximus S1 monoblocks.

Let me put it in this way. It would be so wrong not trying this setup. In one way or another it proved many things floating around in my mind for a long time. One thing is how much difference world-class state of the art component can bring to the audio chain. Takumi K-10 already proved that on many ocasions, but it carries on the same exalted position again with April Music Eximus components. Top class upper echelon preamplifier can breath life and create the power of performance that elevate whole system to a completely new level.

In a combination with Robert Koda Takumi K-10 April Music’s Eximus S1 and DP1 opened up a complete new universe of performance and something to think about in a larger way. Before I’ll get slumbered by good meaning critics let me elaborate. In this combination everything as whole became such a potent entity that it shook my awareness of things high-end at this price range. There was the absence of some particular things related to Class A or Class AB, but with a good compromise.

Where did Class D in this particular case stood out? With high-resolution audio files and vinyl particularry. While there was certain unstressed way of reproducing the music, everything stood out with high-res and vinyl. As if Class D has a nature to work with such mediums.

I cannot declare revolution, but perhaps evolutionary steps in understanding of basic building blocks or high-end audio reproduction and Class D role into it. So far we always had to reach out and pay enormous funds for high quality wattage. In the absence of share power dynamic simplicity tends to break down. I can only agree with Angel Despotov of Analog Domain on the much needed power reserve. Of course in combination with great first few watts. Let me stay away from tube amplifiers on this occasion as they deal with actual power and watt performance in a much different way.

Class D is more often then not seen as something wrong or bad among audiophiles. I think it’s time to debunk the myths and step up in actual testing with a clear and open mind. I’m glad I did so. Eximus S1 led me to see things in more positive and broad way. For a change let us try to go beyond fundamentalist views and see things in general positive way. 


April Music Eximus S1’s monoblocks are carrying the means of something substantial for the present and upcoming high-performance musical reproduction. Like it or not Class D phenomena is happening and I can now understand better why some people already live happily when they combined Class D amplifiers correctly into their system. It made me rethink about the core of present high-end movement and what are the most important things in musical playback. How crucial is the performance linked to the enjoyment? A boundary seems to clearly perplex when it came to what I managed to get from this setup. It was even frightening on the moments how close the whole experience came to reality. Try Cowboy Junkies Whites of Earth now, Donald Fagen Morph the Cat, Police Synchronicity, Dire Straits Hearth over Gold, Weather Report Black Market and so on. Especially with latest high-res recordings ISO SACD’s and high- quality vinyl those album shined with impact that defy quite some aspects of high-end audio reproduction. Great deal of state of the art impact must go to my current speakers. Ubiq Audio Model One designed by Tom Evans are performing like F1 within this setup. Amount of space and controlled bass that no only goes down to the hell, but also defy the midrange. Anyone thinking there is no reference speakers for up to 30 m2 rooms needs to hear those. They’re fall not in high-end but ultra high-end league. And given setup with Model One was not only mesmerizing but a true revelation of things possible within normal living room.

Regarding speakers. There are people living happily with S1 in a combination with B&W 801, power hungry Revel Ultima Salon, top range of Magnepans, Willson Sasha’s and fellow colleague in reviewing “crime” Jonathan Valin who’s opinion I still value much awarded DP1 + Stello Ai700 paired with Martens with The Absolute Sound one of the best sound of CES 2013 award. Stello Ai700 is basically two S1 in one chassis with a preamplifier section and upgraded power supply. I’ll urge highly Dmitry and Simon to send Stello Ai700 for a comparing test.

So from no on I keep my door widely open with much less judging and more healthy perspective … Thanks for Dmitry Valdin of Transparent Acoustic Germany in convincing me to take the whole package for a review and for providing the samples.

I surely didn’t expect that much of inner change :).



DIR(Digital Input Receiver)

192kHz sampling frequency support

Low jitter recovery mechanism for a very low jitter clock recovery

Very high sensitivity differential input circuit

External noise reduction circuit for minimizing transmission errors

ASRC(24Bit/192kHz upsampling D/A conversion)

Upsampling up to 192kHz

THD: 133dB

Dynamic range: 142dB

DAC(D/A converter)

THD: 0.0004%

Dynamic range: 132dB

Power supply

Custom designed power transformer

Very low output impedance

Line voltage selection 100~117V/220~240V

PCB design

Separated digital and analog circuits design to minimize the digital noise


1 USB 2.0, 1 I2S 100 Ohms TTL Level, 2 COAX 75 Ohms, 1 AES/EBU

110 Ohms, 1 OPT


Windows OS with Driver, MAC OSX


USB 2.0, I2S, DIR(AES/EBU, COAX, OPT) Max 192kHz

Front LED Display

- Amber : 44.1kHz/48kHz

- Red : 88.2kHz/96kHz

- Green : 176.4kHz/192kHz


TI SRC4192

Front Panel Select Switch

- Green : 192kHz

- Red : 96kHz

- Off : BYPASS


TI PCM1794A x 2 (Dual Mono) 192kHz/24Bit






2Hz to 95kHz -3dB



Max Acceptable Input 4.6Vrms

Input Impedance 1 MOhms




RCA : 3.0 Vrms@0dBFS XLR : 3.0 Vrms@0dBFS each pin


75 Ohms



Front Filter Select Switch

- LED Off : Filter OFF

- Red : Filter ON


100 - 117 VAC/220 - 240 VAC 50-60Hz


2A T2A 250V 20 x 5mm size


16Watts (Max 25Watts)


208 x 62 x 291mm


3.6 kg (NET) 

Matej Isak. Mono and Stereo ultra high end audio magazine. All rights reserved. 2006-2013. www.monoandstereo.com. ..:: None of the original text, pictures, that were taken by me, links or my original files can be re-printed or used in any way without prior permission! ::..