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XACT S1. The music server you've been waiting for

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#21 Marcin_gps


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Posted 05 May 2023 - 11:40 AM

Any more reviews coming?

Yes, but so far from customers which I think is more valuable: https://www.whatsbes...708/post-872384


There should be one more report this week, and I think especially important for users on this forum, coming from customer who went through a long journey using JPLAY, dedicated PCs with Xeon low TDP CPU, Apacer RAM, Apacer SLC SSD and all upgrades from JCAT including the mighty OPTIMO S ATX PSU. 


I think he won't mind if I quote him anonymously:



What I heard in first 30 minutes I never believed that it could be possible. I thought that a pc based build with all recommended parts (supermicro board without graphic, old xeon without grafic 20W TDP, apacer slc ssd ,apacer industry RAM and all of the best jcat products inkl your atx supply) would sound similar to the xact s1 but with less afford and easy usable for every one without computer skills.


But I was wrong.


The xact sounds unbelievable out of the box. I can’t describe it in words because every aspect in the MUSIC is so special. And I mean MUSIC. Thera are parts in the music that I only know from really good turntable setups.


This device is really something extraordinary. Full respect to your work and your power.


It is not just another product from me. It's my lifetime achievement I've been working on for years.  


Best regards,


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#22 kaka


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Posted 08 May 2023 - 03:21 AM

Interesting. Some of my aha moments


I started with a hackintosh (PC running macOS players) - build by Mark of Antipodes Audio in fact.

I discovered Jplay and got a basic server for that, then reused the Hackintosh to go to dual Jplay servers


Then I spent a time with Roon and HDPlayer (not upsampling, HDplayer sounded better than the Roon player)


Moment 1

Jplay femto came out, and it sounded way better than Roon. Exit Roon

I had it on a single box, utilising a good external linear supply connecting to a Pico board, with the SSDs on Jplay battery supplies. No as good as it gets but not bad


Moment 2

I heard the base CEC CD transport, got one and discovered it had that server beat. Ohhhh

Not much use for 24/96+ and DSD material. A server is better for that


So I had a look at the commercial servers, with a preference for linux and not roon

I noticed that Pink Faun was using the Euphony linux OS, and that the makers of Euphony supply a pair of basic boxes configured from the bios up as server and player.


Moment 3

Got a pair of Summus servers (connected with a JCat ethernet cable of course) and discovered they also beat the old server.

I ran them on external linear power supplies and when I eventually got my third supply I discovered a weakness.

Every power supply sounded different.

And if I had a pair supplying the two machines, and swapped them then the sound altered. The supplies are AMB-R core, Farad and Plixir.

I doubted that anything was optimal.


Moment 4

A high end commercial server should have the power supplies optimised around the sound, rather than plucked off the shelf.

I looked around the Linux and not Roon server field again and went with Pink Faun. Partly as it uses Euphony which I am familar with.

Wow, huge improvement in dynamics and definition, and and ....



So I can well imagine the feedback you got Marcin

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Linear+battery power supplied WS 2019 server - Jplay Femto, AO 3.0, Fideliser - Jcat XE USB board+Optimo Duo - JCat Sign.USB - Chord MScaler- Stereolab/Blackcat Tron spdif - Chord Dave

#23 Marcin_gps


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Posted 09 May 2023 - 09:03 AM

Thank you for your comment. 


I use Esoteric Grandioso K1X SACD player as a reference point in my setup. It's arguably the best SACD on the market. Sounds very good, but more digital than XACT S1. 


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#24 t.arni



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Posted 11 May 2023 - 09:02 PM

Hello Dear Jplay/Jcat Friends


For anyone who may be interested, I would like to briefly share my experiences with the XACT S1.


About my history with Computer Audio:

I have been involved with computer audio for more than 5 years. I was trying to get the maxiumum out of an Single Audio PC and my final setup was:

Supermicro server board

XEON low power CPU with about aprox. 20W TDP

Apacer Industrial RAM

Apacer SLC SSD

JCAT SATA cables

JCAT Signature LAN and USB Cables

And of course all the accessories from JCAT ( USB XE + LAN XE ) Optimo 3 DOU for USB and LAN Cards

AND the OPTIMO S ATX power supply from JCAT, which was another huge step forward.


I tried several Windows Server versions (2019 - 2016 - 2012) in Core mode  and Gui. Contrary to many other opinions, I ended up with 2012 because it just sounded the most natural to me. Yes 2016 has more attack and the bass is more on point (too much?) but overall 2012 has the most natural sound for me.


At the end the sound was really very good ( I thought ). I work in a high-end hi-fi shop in Vienna and have a good overview of what is currently possible on the digital and analog side with the well known brands. I have to honestly say that I am of the opinion that the good old vinyl  turntables with really good cartridges and phono amplifiers is still the measure of all things. (for me)


But: What came out of a PC setup with JPLAY, Audiophile Optimizer and the JACT products was really very good (at least that's what I thought)

When Marcin then announced the XACT S1, I was of course curious and ordered one to test. I was very skeptical. The small thing can't possibly sound better than my Monster PC setup with the 30 kg ATX power supply S ATX.


But what should I say:

After the first few notes it was immediately clear: This sounds clearly better than anything else I've heard from a digital source.

Sound is always difficult to describe, but I'll try:

In short: Everything Marcin has described so far is true. Any rest of “digital” sound is gone. In my opinion, this is best heard on cymbals. Cymbals sound as real as I've ever heard from a digital source. Voices have a texture and energy that is incredible. The immediacy of the piano attack is so real as never before. And so on….

Long story short: It just sounds “analogue” and perfect to my ears. The right tonal balance between warmth and details - unbelievable spatiality - absolutely black background.

The perfect sound: Everbody has another imagine of what sounds perfect. One loves the analytic way of “disassemble” music and the next loves the sound of “bad” tube amps without any kind of resoloution and details. So who is “right”. I love the organic way of listening to music. And for me marcin gets the point to 100%. But this doesn’t mean that it would be the perfect server for everyone

If you have the sound of a nearly perfect vinyl setup as a reference in your ears, you should try the XACT S1. That is what I can tell you with a clear conscience


I really don't want to advertise Marcin here. I just wanted to share my enthusiasm for the product and draw attention to the fact that this is really an extraordinary product (to my ears ;-)


Happy listening , Thomas


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#25 PavelD



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Posted 19 May 2023 - 06:08 PM

it looks like an excellent solution, unfortunately I can't release that much money right now

#26 Mentanalyste



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Posted 26 June 2023 - 12:42 AM

Hi Marcin,

Thank you for the details and your work. It is fascinating.

I understand that you have developed a specific version of JPLAY under your own real time Unix OS.

In the Windows version of JPLAY we had many configurations and in particular:
- DAC Link
- XtreamSize
- Bitstream
- etc...

My questions:
Do we still have access to its settings?
Are you running JPLAY with unique settings, if so which ones?

Personally I have the DAC MOLA MOLA TAMBAQUI. I have configured JPLAY with all the extreme options.

Hi Marcin,

Thanks for this information. It is perfectly clear.

Interesting about the speed of the DAC link ;-)

Can't wait to get my hands on this fabulous device.

See you soon

#27 Marcin_gps


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Posted 27 June 2023 - 10:37 AM

Great :)


New customer reviews can be found here: https://www.whatsbes...708/post-883576


Best regards,


Follow my hi-fi journey on YouTube

JPLAY FEMTO: a complete network music software player for the most demanding audiophile.

Want to squeeze more from your PC-audio? Hear the difference with JCAT
Join Computer Audio Enthusiasts group on facebook

#28 joseph01y



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Posted 16 July 2023 - 06:43 AM

I am an audiophile from Taiwan, and I have always had a strong interest in audio equipment。

I have been using the Jcat Xact-S1 digital player for the past week, and I am very impressed with its performance. I have been using a Pinkfaun 2.16 streamer for the past 12 months, and the Xact-S1 is just as good, if not better. The Xact-S1 is also much more affordable, and it is much easier to use.

The sound quality of the Xact-S1 is amazing. It has no digital sound, and it sounds very natural and analog. I have been listening to my favorite music with the Xact-S1, and I am blown away by the sound quality.

I highly recommend the Jcat Xact-S1 digital player to anyone who is looking for a high-quality, affordable, and easy-to-use digital player.

Here are some of the things that I like about the Xact-S1:

  • Excellent sound quality
  • Affordable
  • Easy to use
  • Supports a wide range of audio formats
  • Has a built-in DAC
  • Can be used with a variety of speakers

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#29 timd



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Posted 05 September 2023 - 09:49 PM


Long-time follower of JPlay and the PC DIY server builds.

My DIY server was a single pc setup. HD Plex psu with 12v direct to CPU. 19v to HD Plex 250w Hi fi ATX dc to dc. This connected to ATX only of MB only.

5v outputs to two JCat Optimo Nano’s. These powered SSD’s for OS & music drives, and supply to JCat USB XE.

JCat USB XE card for output to DAC. SATA cables JCat, original. ATX & power cables, Ghent Audio.

JPlay, AO, & Fidelizer running on W server 2012 R2.


The JPlay route to improving pc’s audio to achieve better music reproduction has given me years of slow steady progress towards a far better musical experience than I ever experienced before.

Many ups & downs along the way with huge frustrations but, outweighing all of that, the rewards were fantastic.  Not being that IT savvy, I have relied on the forum heavily for technical guidance on this journey & the many topics with their contributors without which, I would never have succeeded. 


Current system

Lampizator Big 7 Dac. Balanced with volume control. ATC SCM 50 Active speakers.

Ideon 3R Master Time Black Star Clocker, JCat XACT S1.

Puritan PSM 156 power conditioner, supplied by a 5kVA balanced CTE isolation transformer on dedicated hi fi circuit.


I’d been considering a purpose built server for the last few years, but from those I had heard & their cost, I had not really thought it a viable route. I had never been particularly impressed by the sound quality of any I had experienced, particularly against what they cost. Having said that, most severs I had experienced had been via shows etc. so not the most ideal environments.


Always happy with my DIY build & in terms of cost & hands down a musical winner. However, from time to time it did let me down, which required intervention on my part to resolve whatever the issue may be. Having had my server for 10 plus years, it came time to decide whether to build a new server or go for dedicated purpose built unit, the latter being decided upon.


So the journey began. Ruling out the big manufacturers based on what I’d been hearing against cost, I looked at the boutique side of severs; based on either tweaked Windows OS, or bespoke OS.


I did demo a unit at home; a Windows based server with various options in terms of PSU, cabling, SSD’s & various other options including software tweaks for adjusting sound to taste.

I had the demo unit for several weeks & it sounded pretty good. After some communication with the manufacturer, a few tweaks & and software changes, things improved further but with a cost between 7 to 10k depending on options, it was a lot to invest.


My existing server bettered the demo unit in some key areas & overall, my server won out.


Enter the S1.


As a Jplay follower for years, I noted the release of the S1 & read various comments by those that had heard the S1. Could this be an option?

After many emails & questions to Marcin I decided to try the S1. Marcin must have got fed up with so many emails & questions but he dealt with all promptly, answering my specific queries in each case.


The S1 duly arrived. Hook up was a breeze. USB, LAN, SD card & power. I had a network issue to start with but all was resolved & again, Marcin was on hand via email, (he was actually on holiday with his family but still took time to answer any queries, so many thanks for that).


To be clear, I only used the S1 with music stored internally on the SSD. I have yet to get into streaming in any significant way.


Straight out of the box, the S1 sounded good. It bettered anything I’d previously heard at home. The initial standout for me was space, & air with the strands of the music occupying a more convincing sound stage, all sounding bigger but with more air & space around the music.


Decay of notes be they synthesised, acoustic, amplified or whatever, is excellent. With live recordings, the sense of the venue is more apparent. A friend of mine uses the term “plankton” to describe the small details in the sound stage, light & shade, micro details & atmosphere. It’s an appropriate description. All the small details you are aware of in recording are just more “there” with the S1.


I listen to a lot of electronic music & the layering, panning, & detail is excellent. You can just hear further into the mix. This is not forced details, not edgy at all. In fact, compared to my server, the S1 is more natural & relaxed in its presentation yet with detail/plankton in abundance.

Bass is also richly textured allowing more information low down to be heard. Listening to double bass live on a good recording was a revelation. The attack, sustain & decay along with the sound of the strings, the finger board & body of the instrument are all well-defined & make the instrument come alive in your listening space.


The S1 is pretty music agnostic. Even with poor recordings, in most cases the ability hear further in to the recording makes poor material more palatable than before.


Changing USB cables between S1 & DAC was interesting. The S1 clearly shows these differences.


The Master Time Clocker has always brought significant improvements to whatever server setup I’ve used during the upgrade process over the years. Now with the S1 in however, I’m not as convinced.  I’m not ready to sell on the Master Time Clocker yet. The Master Time adds a bit more weight to the presentation, but at the expense of stage width, slightly compressing the presentation.


I’m pleased I took the plunge with S1, albeit a major decision financially, I have absolutely no regrets. I know Marcin is still working on user & OS upgrades, so I’m looking forward to that.


Ease of use, exceptional sound quality. What more could you ask for.


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