JCAT OPTIMO S ATX Computer Music Server Linear Power Supply Review

JCAT OPTIMO S ATX REVIEW website 1 linear power supply

This is a review summary written by Terry Ellis June 2022.

For my video full review please see my YouTube channel link here 


I have been a computer audiophile for more than a decade, that means I have a serious enthusiasm for building computers dedicated for music playback and optimising them to fulfil just that one role to the highest level a computer possibly can. 10 years ago things were very different, the concept of a linear power supply sounding better than a generic computer supply was questioned.  Today in 2022 nearly all manufacturers of music streamers and servers employ linear power supplies not because its a trend, not because its cheaper, it is often more expensive but because the sound quality improvement warrants it.

What’s very important to remember is not all linear power supplies are created equal, I used to believe that all linear supplies would be the same but I have since compared many and there are some very distinct differences in their performance such as I demonstrated in a video here

Linear power supplies have become very popular and readily available, at least here in the UK and they are mostly designed for powering devices like DAC’s and audiophile ethernet switches products that have fairly simple requirements, a single voltage with a low current draw. These supplies can be made cheaply which is great however better designs with better performance will cost more.  Powering a computer requires something very different.  For starters the voltage requirements are 12v, 5v and 3.3v and at times the power current draw can be very high depending on the computers components, most notably the CPU and GPU. The power draw is also not constant like a DAC, it will fluctuate depending on what the computer is doing, the CPU duties are varied, its load is varied so its power draw will vary.

Then we also have to consider the ATX standard that was developed by Intel back in 1995 and developed since.  The ATX standard ensures different manufacturer products such as motherboards will all work with other manufacturers power supplies and peripherals, an industry wide standardisation.  I bought the first ever ATX linear power supply, designed for powering a dedicated computer music server with sound quality as a priority. Its physically big and heavy, features nice components and can deliver 400 watts of power.  I have been using it for the last five years and have been mostly happy with it.  What I did know is that better power supplies have been developed since, but I didn’t know it was not a fully linear design, not a fully linear ATX power supply.

Size comparison OPTIMO S ATX underneath my current 400w linear supply that used to seem huge to me


The JCAT OPTIMO S ATX is the worlds first fully linear ATX power supply, there is not a single switching component within it, even the control board has its own  linear power supply. Like all JCAT products its designed to push the boundaries of computer audio to a new level, I have always admired any manufacturer that is trying to be first, do more and go further and Marcin at JCAT always is.

Full disclosure here I have been a user of JCAT products ever since the company was formed, this was before I started my YouTube channel and started reviewing HiFi. Today I use nearly all of JCAT’s products and some I use multiples of.  To be clear I am not paid to use them, some I have been fortunate to keep after a review but many I have bought myself.  I use them because they always work as described, they always make my music server sound better such as I demonstrated here. Marcin has an ear I trust and as such I have full confidence in the products he sells.  However that does not mean they get an automatic pass from me, I test them just as vigorously as any other product in for review and quite often more vigorously as each review is a home audition because each new product I am considering the purchase of.

When the OPTIMO S ATX arrived I was stunned by the size of the box it came in, I knew it was going to be big but I was not expecting this big or this heavy.  The box dwarfed that of several amplifiers I had here and the weight, 27kg for a linear power supply is no joke. I think its best to think of the OPTIMO S ATX as an amplifier, a big amplifier in terms of its physical size and weight, you will need space for it that is for sure.  A big part of my listening room renovations at the beginning of the year was to give me more rack space to allow me to review this power supply.  It was still a squeeze fitting it in due to its depth, but it did fit without me needing to move my racks, maybe it was fate telling me something.


Looking at the rear of the OPTIMO S ATX  is where things get interesting, on one side are a set of computer ATX power supply connections such as the 24 pin for the motherboard and 8 pin for the CPU. But on the other side we have 2 independent speakon power outputs one for 5 volt and one for 12 volt meaning the OPTIMO S ATX can power peripheral devices as well as the computer music server,  its acting as several linear power supplies in one.

One thing that stood out to me straight away is the exceptional build quality. Every OPTIMO S ATX is hand built in Poland and comes with a set of cables.  The cables are immense compared to what you normally see even from audiophile power supplies, but importantly they are still flexible. JCAT say they are using as thick gauge cable conductors as they possibly can (I assume the limiting factor is what the the connections can take) and also using very good quality materials. The cables are shielded and there is a little pin that allows you to earth or ground the shield back to the earth ground of the power supply unit, we have not seen that before. The shield doesn’t run fully from end to end which at first disappointed me a little, until I installed them and realised its to allow the cables to bend over near the main connections to fit into slimline cases.  I have a case like that so its an essential part of the design and I think shows how well things have been thought through.

The best bit for me;  if you have ever built and then taken apart a computer you have experienced this I am sure. Normally when you try and remove a cable connection such as the motherboard 24pin its clamped so tight you have to wiggle and get your nails in there and I end up pulling overly hard to get the connection to release, it’s a horrible experience but its been the same on every computer I have ever built, lots going back decades. This is not the case with the JCAT power supply the cables connect and you can remove them really easily and trust me you will appreciate this difference.

But even though the OPTIMO S ATX is big and designed for purpose and has several huge custom toroidal transformers that are magnetically and electrically shielded, more capacitance than a lot of big amplifiers and big heatsinking its not huge in terms of watts power output, especially compared to modern gaming computer power supplies that can deliver a 1000 + watts from small packages.  That is why switching power supplies are used in computers for their efficiency and power delivery from a small size.  The OPTIMO S ATX can deliver a very high amperage of 23 amps which is a lot and comfortably enough for modern computers, especially with audio playback use in mind, delivering about 500 watts of power, again that is more than enough. But it wont be enough for big graphics card gaming, its not designed for that I think that is very important to point that out. Its designed to deliver really clean and stable power consistently up to its maximum rating and that is the reason its so large and well ventilated because there is a lot of heat sinking needed. It reminds me of a Pure Class A Amplifier and we all know we want one in our systems, but it didn’t run nearly as warm as I was expecting but maybe with a higher load it would.


Setup is very straight forward if you are used to building computers and you likely are if you are considering the purchase of the OPTIMO S ATX.  You simply replace your existing power supply and cable to the computer as usual and in my case the end result was neater and tidier than before.  The quality of the included cables fills you with a lot of confidence through the process, even after applying a heavy bend to get the cables to fit into a slimline case.  Everything powered up first time and I like how there is an obvious click when the OPTIMO S ATX powers on from standby, its reassuring to have an audible cue that something is about to happen. Of course you also have the change of the front LED from blinking to solid on and I am not a big fan of the LED blinking so leaving the computer on all the time for best sound has never made more sense to me.

There is a ground lift switch on the rear which I left as is for the review with the ground lifted. The OPTIMO S ATX was silent in operation where as my old linear would buzz very audibly from 1-2 feet away.

For testing sound quality I wanted to keep things as like for like as possible because as I mentioned yes this is a review, but its also a home demo for me and I wanted to know if the OPTIMO S ATX was better than what I had and by how much.   I only used the main ATX outputs I didn’t use the independent 12v or 5v outputs, that also meant I continued to use the JCAT OPTIMO 3 DUO Linear power supply powering the JCAT USB XE and NET XE cards in the music server.

My initial first listening impression was that my system sounded like someone had taken a cloth with a strong detergent and like a window cleaner removed a glaze that was on the glass stopping me from fully looking in. I know that is a cliché thing to say but that was just my first impression. As I listened more I felt like the treble had been set free and was now more present clear and easier to hear and I don’t mean brighter, I mean easier to hear, the details of cymbals or other high frequency information was presented more clearly in the overall sound stage or maybe with more pop. I also felt the sound stage was more open and spacious, vocals sounded a little further back in some music and in more space which is always great for me because I don’t have a lot of space. Interestingly music seemed to be cleaner, and more open but also with a lot more energy to it, it sounded larger or grander with some music or maybe more attacking and impulsive with other music, I wasn’t expecting this. I was actually expecting the opposite for it to become all softer and more set back but I realised that is not how real music is and I listen to a lot of lively and energetic music so lively and energetic is what we should be pursuing, not soft.

There was lots of other good things happening that I was enjoying but the systems balance had shifted a little bit which didn’t surprise me because if you clean the sound from top to bottom you remove some “fat” from the sound, bass tightens up significantly but then is a little leaner. I have been setting up systems based off my old linear power supplies sound for years so I had to make a few changes and for me that means changing how the system is balanced using Dirac Live and changing some buffer settings for the Singxer SU6 digital convertor.

After spending a bit of time on this I was able to unlock the next level of sound quality from my HiFi system, bigger and better bass, a bigger sound overall with much more resolution clarity and energy and it was definitely a very obvious step forward from where I was before in nearly every regard.  I could hear where if my listening room was wider I think I would have been in for something even more exciting but as it was all music was cleanly delivered with exceptional timing and precision and with incredible placement specificity to the sound stage. I was also getting silly greedy with the volume on the Audiozen Embrace amplifier because the sound was that much cleaner, its fun to really crank the volume at times.


Following my video review and taking the advice of Marcin from JCAT I changed things and powered everything in my computer music server from the OPTIMO S ATX.  That meant removing the excellent JCAT OPTIMO 3 DUO linear supply and this was extremely difficult to do because in my mind the best way to power things is as separately as possible, with a different linear powering different things for the best performance.  I think this was the best approach until now, the OPTIMO S ATX changes this and powering everything from it produced my best HiFi sound to date by some margin.  Now everything was improved from before including the all important musicality.  I created a sound demonstration video to give the best example of this I can, I think the video has exceptional sound quality and that is just a recording, in the flesh you can imagine how much better it is.  The video is below if you would like to watch it, remember like all recordings the better the playback system the more of the recording you will be able to appreciate.


Who is the JCAT OPTIMO S ATX for and are there any negatives. Firstly it costs 5175 euros inc Worldwide shipping, that is a fair old chunk of money and initially seems like a hell of a lot of money for a linear power supply in general, but this is far from a general supply.  I own 6 other linear supplies and none of them are even remotely comparable to it, the difference in the actual product, the design, the components used and the size and technical performance I am not sure anything currently compares, its currently in a class of its own. I said it earlier, something I have learnt through experience, its not a linear power supply that’s making the difference it’s a good linear power supply that will make the difference and they are not all created equal and this kind of quality costs.

However regardless of how good this is clearly not going to be a product category or price level for every audiophile and you are going to need to clear some space for it. For me that is the only real potential negative, the size. If your not setup already to accommodate it that might mean some big changes to your equipment rack setup and that might mean additional costs and work.  Just make sure you measure twice and cut once as the saying goes.

I think the OPTIMO S ATX is for computer audiophiles just like me, who are deep into it and looking to push their HiFi system source as far as possible because they know the benefits and importance of the source, it can only get worse from there, not better. Marcin at JCAT feels a lot his customers will already have very good HiFi systems and the OPTIMO S ATX will remove a huge bottleneck of that system they might not have even realised they had. Based on what I have heard I definitely agree with him, its taken my system to a whole new level of sound stage, imaging and most importantly realism.  For me its been the difference between listening to a well optimised computer to now listening to the highest levels of digital source which would normally cost far more money than I could ever afford. In saying this I do think you will need an excellent HiFi system setup very well to fully realise what the OPTIMO S ATX can do and on that I feel like I have only scratched the surface of the benefits I could get from it and would need more to time to fully realise what it can do as I get more used to what its allowing me to now hear, allowing me to become better at optimising how I setup HiFi systems in my room.

I have heard enough to convince me it would be worth purchasing an OPTIMO S ATX for my system and it would be great for doing my job.  However I also think if you are just getting into serious computer audio playback, I appreciate this would be a big initial step but looking back to when I started there was nothing like this available, literally nothing even close. Had this power supply been available, when I think about how much money I have spent with the 7 I think now different linear supplies and about 5 different batteries supplies I have bought over the years that would collectively all cost about the same. The others are all now surpassed, most are in my loft gathering dust, so again yes the OPTIMO S ATX is big chunk of money but its easy for me to recommend it because its improved my systems sound in every area and simplified it too.

pecial Performer Award Website No Background

A Special Performer Award is Pursuit Perfect Systems highest accolade and is in recognition of exceptional product performance regardless of price

For the full specification of the JCAT OPTIMO S ATX see the website here