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Massively improve audio quality on your Windows PC with any application, Tidal, Spotify, Qobuz, and other streaming services.

"Fidelizer resulted in the biggest single improvement to my hi-fi that I have yet encountered!"
Nick Whetstone, TNT-Audio
For the first time ever in Windows, take full advantage of multimedia realtime framework optimization of "Core Audio" to improve Windows audio performance. Fidelizer helps revolutionize Windows audio quality at the foundation level and works well with JPLAY/Audiophile Optimizer.

How Fidelizer Works

Fidelizer is a very simple tool to use. You just choose the optimization level, click “Fidelize”, then sit back and enjoy the music. You can also choose to Customize, to picking individual optimizations by yourself to find the optimal point for your system with other optimizations. Fidelizer could do the following functions below:


Fidelizer's Core Features


The default configuration sets to “Workstation” limiting the optimization to unleashing Core Audio parts such as MMCSS and system timer for better audio performance. You can also raise the optimization level to perform other functions, like controlling processes and stopping services, freely because Fidelizer doesn’t make permanent changes to your system. You can give it a try without taking any risks at all. There’s no chance to harm your system.

Let’s see how the system works before applying Fidelizer optimizations. To make things simple, we’ll classify resource utilization into audio tasks and non-audio tasks. Based on Microsoft’s Multimedia Class model, we’ll treat non-audio tasks as System or Network tasks. Most systems would look like this:


Before Applying Fidelizer


We’ll divide the work evenly for easier understanding. You can see that the audio is represented by the big speaker, playing multimedia files, the system by the graph, running services and tasks in the background, and the networking on the bottom, doing some web browsing and streaming content. After the optimizations, your system will have improved audio performance by concentrating available resources, like this:


After Applying Fidelizer (Workstation)


As you can see, audio will have more resource utilization after using Fidelizer and can improve further with higher optimization levels. You can learn more about each optimization level in detail by reading the User Guide, including options and features from the upgraded versions. All changes made by the free version will revert back to normal after system restart. You can improve Windows audio quality this much for free.



Yes! You can get this for free with no trial because the developer of this software wants to change the world of computer audio, where most audiophiles pay for OS X audio software. The thought of OS X being considered the best audiophile solution is unbearable while there are so many contributions on the Windows side, such as:

JPLAY – Ultimate Audio Output module for Windows, works with most audiophile players through ASIO
AudiophileOptimizer – The best way to turn the most powerful Windows platform to a dedicated audio server
Bughead Emperor – One of the most powerful audiophile players and includes data storage optimization

And of course, Fidelizer, too. They’re made by truly passionate audiophiles.


Now we have bit-perfect playback software. How can Fidelizer make it even more perfect?

In the past, Windows rendered audio through its software mixer so it could render multiple audio sources with different sampling rates and hardware connections through re-sampling, down-mixing, and some audio effects. Since there was a strong demand from DAW use for audio playback without altering data (like for monitoring), ASIO was created for that kind of unaltered, bit-perfect audio playback.

Originally, the concept of “bit-perfect” was just about sending data to audio devices directly without manipulating the data. I don’t understand how it’s escalated to “perfect digital audio transport” as some people think of it today. If you compare bit-perfect computer audio playback to audiophile CD transports, most CD transports shall have bit-perfect playback and we would have obtained the holy grail of digital audio 30 years ago.

Being bit-perfect is better than not be for most of the time, but that’s all there is it to it. You can see debates about bit-perfect involving some software from time to time like recent disputes between J River and JPLAY. Since I don’t want to join the fray, all I can say is use your own ears and judge for yourself. Some people don’t hear differences between audio players and some do between WAV/FLAC and there’s nothing wrong with that.


Enjoy music with Fidelizer? Consider Fidelizer Upgrade Program

To further extend products and services, now Fidelizer can be upgraded to do more without limiting to not perform any changes to system at all.

Right now there’s two versions of upgraded Fidelizer, Plus and Pro. Based on Fidelizer Pro, which is the most advanced version, you’ll get the following benefits over the free version:

  1. Choose whether to apply optimizations one-time or choose startup optimizations.
  2. Core optimizations are reworked for better audio performance and more flexibility for all kinds of audio playback.
  3. System configuration can be applied with unique tweaks for better audio quality
  4. Program UI has been reworked to be more friendly with computer audio server projects.
  5. Optimizations will undergo improvement updates over time, follow along with new Windows versions and allow for changes based upon user feedback.

You can read about the individual product’s features and ordering details, including pricing on the Fidelizer Upgrade Program page.


Is there some kind of way to test it before buying it?

While it’s understandable that some customers prefer to evaluate test versions before purchasing, we decided to focus on improving product quality and services rather than limiting product features. We don’t favor the idea of making trial version with the limited features. It will later become constraints to further improving software.

The developer put great effort into building good quality software for free. If you trust in the free version’s performance being something worth paying for, you won’t be disappointed in what Fidelizer Upgrade Program can offer you. Up until now, there isn’t a single customer who’s not satisfied with Fidelizer’s performance after upgrading. You can read reviews and what other customers say about Fidelizer and make up your mind later.



Since moving Fidelizer to a new home, there have been requests to send copies for product review by a few respectable audiophile websites. Some are kind enough to give us a review about Fidelizer products, as below:


Audio quality is important! And Fidelizer makes sure you enjoy the best audio quality possible.

I also use a neat little shareware program called Fidelizer that optimizes various background computer functions for music playback. This brings me to another point.

Many of you may already know that best track production quality with high fidelity is not attainable unless you customize your high-end system to fit the needs. Since PCs are not cut out for such heavy tweaking with layers of recorded sounds through music production software, you’d need a tool like Fidelizer to get best results out of music software you’re using.

AudioStreamThe improvements to the sound while listening to JRiver and Foobar were quite obvious to me. The soundstage became much wider and deeper; the bass was now better defined. Focus and definition improved with an added bonus; a slight midrange hardness I have heard in JRiver was now gone. I also observed that JPlay continued to work with Foobar2000.

Mono and StereoThis a marvelous piece of work that also puts the average sound system to a harsh test. With the Fidelizer performing its magic, the sound certainly benefited enormously: the large scale, complex music was handled extremely well, with exceptional separation of the individual instrumental sections, with lots of air around them and with gorgeous brass and string tone. Everything sounded vivacious, dynamic and very exciting.

PCAudioI really like with my Audio PC setting. With AudiophileOptimizer 1.30, it gives extra impact on sound. Current my best feedback setting is below…

– Client PC : Windows 8 (not 8.1) + Fidelizer Pro 6.1 + JRiver 20/JPLAY 5.2.1
– Audio PC : Windows Server 2012 + AudiophileOptimizer 1.30 + JPLAY 5.2.1

I think it is the best sound I ever heard with my Audio setting. Very clear background and close to perfect image (I assume there is no perfect with Audio since every new technique comes). Especially, when I listen big scale symphony like Mahler Symphony No.2, I can hear different stage of music. Better dynamics and better image. Thank you for great software.

I may need more time to conclude testing, but I can say Fidelizer Pro definitely help my PC Audio life.

Thank you,
SH Yoon

Fidelizer is a nice little utility for those who enjoy music and use audiophile players like Foobar. I did notice some difference with the sound quality.

TNT-AudioThere is clearly more transparency, enough that you don’t have to listen for it. The music comes from an even ‘blacker’ sound stage, and sounds relaxed but not soft. It’s as though you have been listening to your hi-fi just outside of the room, and then gone in and sat in front of it. This is not one of those tweaks where you need to listen for a few days to realise that something has changed for the better. And there’s the bonus of just being able to turn on the computer, open your music player, and be ready to play back some music. Fidelizer resulted in the biggest single improvement to my hi-fi that I have yet encountered!


What customers say about us

To ensure you’ll receive good quality products and services, I’d like to share what customers say after trying our Fidelizer Upgrade Program. These are quoted from their feedback without changing any content so feel free to read it.


AudioStreamThe improvements to the sound while listening to JRiver and Foobar were quite obvious to me. The soundstage became much wider and deeper; the bass was now better defined. Focus and definition improved with an added bonus; a slight midrange hardness I have heard in JRiver was now gone. I also observed that JPlay continued to work with Foobar2000.

PCAudioI really like with my Audio PC setting. With AudiophileOptimizer 1.30, it gives extra impact on sound. Current my best feedback setting is below…

– Client PC : Windows 8 (not 8.1) + Fidelizer Pro 6.1 + JRiver 20/JPLAY 5.2.1
– Audio PC : Windows Server 2012 + AudiophileOptimizer 1.30 + JPLAY 5.2.1

I think it is the best sound I ever heard with my Audio setting. Very clear background and close to perfect image (I assume there is no perfect with Audio since every new technique comes). Especially, when I listen big scale symphony like Mahler Symphony No.2, I can hear different stage of music. Better dynamics and better image. Thank you for great software.

I may need more time to conclude testing, but I can say Fidelizer Pro definitely help my PC Audio life.

Thank you,
SH Yoon

Hi Keetakawee

Well it is early days listening, but all I can say the Pro version, is just WOW! And by a considerable margin over the other versions, by some margin I might add… The pro version is worth every penny….

Immediate observations include, improved soundstage, better dynamics, textural tone and rhythmic interplay is a considerable improvement. Sublime bass extension. Vocals appear from a silent darker background with amazing depth. Believe me the system already sounded pretty damn good before the software tweaking. Fidelizer Pro turns my Mac Mini, running bootcamp and windows 7 64 bit, into a musical time machine…..takes the music where ever you want it to go.

The above is said in context, that the system was already revealing, room matched and well-balanced….excellent system upgrade, thank you!

2012 Mac mini, SSD, 8Gb Ram, Win 7 64 bit (bootcamp)
USB (Total Dac D1) out to Zodiac Platinum Dac 8x up sampling
Zodiac XLR analogue out to Trinnov Amethyst DRC
2.2 Setup feeding Linn Klimax 320A speakers and JL Audio Fathom F112 subwoofers

Alan Evans

Alan Evans

I am very happy to get the Pro version without any regret, and 100% money worth. Thumb up. There is improvement with subsonic low and high frequency with much purity sound.

Alfred Chen (JPLAY/Audiophile Optimizer)

Hi, Just loaded it and have it running now. It sounds great. Seems very smooth and resolved. I am running in Audiophile mode/JPlay local.

Bob Flood (JPLAY)

Hi Win X:

A nice, very easily heard improvement. I would best describe it as a much more relaxed presentation, a layer of glare removed.


Bob Holzer

This seems to be working better, and it sounds better than ever. I think that if you don’t select the device you are using for sound as the default, it will be shut off. Only got to listen to it for an hour. Another step closer to analog with the best aspects of digital included. Lots of space and subtle details. You do know how to listen. Can’t wait to get my tricked out Geek Pulse DAC with 82 Femtosecond clock. Still need Fidelizer if the jitter is modulated by the computer.

My reaction to listening to Fidelizer 6.1 Pro is being relaxed, closing my eyes and listening. I can’t remember being able to do that before. Job well done.

Brad Connery (JPLAY)

Hi Keetakawee,

Well… you nailed it! :)


As the Fidelizer free/pro – A/B test is very difficult to accomplish (just with two exactly equal computers), what I did was:


  • Listen a FLAC file with Fidelizer 6.5 free
  • Listen the same track on the CD player

The difference between the two was obvious yet subtle (not night and day): the CD was more detailed, more accurate on the time domain, with better attack, and with a wider stage



Reboot netbook, and install Fidelizer Pro: Extremist and Network Render, and repeated the previous test. Well, the difference between the FLAC – CD, is now more subtle then ever! The precision in the time domain improved, the clarity also, the stage is similar to CD. Despite I believe the CD still have a little more attack and transparency (very subtle), my computer audio source never sounded like this before!


I know that my configuration (Network render) isn’t the best for top audio performance, and I believe that if we choose “Media Server” something is improved. But this setup is the best for my needs…


In overall, what you did is amazing! Definitely your work must be rewarded.


Carlos A.

Carlos Aniceto


Thanks for your fast service. Fidelizer Pro is working faultlessly and definitely a worth it upgrade to Fidelizer. Works great with JRiver 20 and allow to fully exploit the real potential of my HTPC.

On the audio side has upgraded the mid range to an absolute transparency, bass is tighter and fast as treble is extended and silkier. Everything is where it should.

Best regards,

Carlos Espadinha

Hi Windows X,

Thanks for the build, it has made a great improvement, especially picture and sound as I run video and audio through JRiver.

Corey Nixon

Thank you very much, it works really well and it seems to consume less resources than the normal version.
Not having to start it up each time is the main reason why I bought it, was not actually expecting better sound :)

But somehow the sound is also a bit better, fascinating (this with Windows 2012 R2 Core, CPU and RAM @ 800 Hz).

Dan Corlateanu (JPLAY)

Here are some comments after using Fidelizer Pro this week.

Am using an Acer i3 laptop – 8 gig ram – win 8.1 with an IFi Power USB. I found that after a clean install the Fidelizer Freeware program sounded even better. Now with Fidelizer Pro the sound quality has improved again immeasurably. With latency down to 4 on an i3 this is more than I could have dreamed for.

Korg Audiogate 3 Requires network support with Win 8.1 but not with Win 7? The soundstage appears big and highly detailed and although very impressive through the Korg DAC – it is tiring after a while. Being able to use DSD files created from my Korg MR2 recorder does give an edge when comparing commercial DSD file downloads to my files and the Fidelizer Pro provides even better SQ. Foobar 2000 Files now have a natural soundstage with a high resolution noise free background which allows the music to flow freely.

From what I have heard from Pro with this program it could become my de facto standard in the future. Jplay Still unable to play DSF files without stuttering. So after a few days experimenting with Pro I am delighted with the results. I congratulate you on creating a program which brings me the closest I have ever been to the music I love.

Kind regards,

David Lloyd (JPLAY)

Great job! I also had my brother & friend buy your product system never sounded better  fast service.  Dean from Canada! They are also very very happy with Fidelizer Pro worth every penny!!!!!!!!!!!!!

Dean Labossiere

I’ve installed Fidelizer pro 6.1 on my HTPC and everything is OK.
Audio is very good, as I’m using JRMC 20 as VDM driver and DVDFab plyer for playing DVD or Bluray.
This little media player has a very good video quality equal to JRMC with Red October HQ filter and it offers menu for Bluray.

For the moment I’m using Audiophile level for Media Center (HTPC, Audio/Video/Network player), black are deeper with better definition and more “grain”.

Dominique COMET

Improvement on the audio pc is great, i have done a great jump forward. Thanks a lot ! When my new control pc will be ended, will sent you a new order. Good job!


Frédéric Cugnet (JPLAY/Audiophile Optimizer)


Small return on tapping.

I am currently running with Jplay6 beta5, simple PC and fidelizer pro 6.5 under Windows 8.1, Intel I7, 4 double cores at 2.2 ghz. To me, your optimization software is a must, I did not get better, my pc runs with an impressive silence, no breath, no fan, nothing but great music, which is a tour de force with such a processor.

I did a demo with audiophile friends, all agree, is excellent. One can even compare, WAV, FLAC, AIFF and AIFF … winner for me.

Joseph and Marcin are also very, very good job. Too bad you can not get together to assemble a pc marketable audio configuration, I’m interested.

I read all the post about you and confirm you are very good.



Gérard Maitre (JPLAY)

I managed to get the program installed before I left for work. It sounds really good…smooth and musical.

John Kessel

Great product! Really makes more different to the sound with my setup than ‘replacing all the cables’ Very pleased!

Juan Diego Puerta Marin

I downloaded and installed Fidelizer Pro.  Since I use a PS Audio Perfect Wave II, I set it up in Network Transport mode.  The sound improvement is greater than that of standard Fidelizer, a broad and high soundstage when I have set the absolute phase switch correctly.

Julius Moshinsky

I have used Fidelizer before (F4 & 5) with good results, see copy of a post from JPLAY below. After more listening today F6 is clearly a further improvement. F5 Extremist did not really work for my system, but with F6 the Extremist option provides a further significant improvement in SQ.

Kjell Nedrebo (JPLAY)

It`s early morning here in Norway and I had a long night listening to a lot of my favorite artists. Jan Garbareck – Cassandra Wilson – Miles Davis – Bill Evans – Dire Straits – Shawn Colvin – Rachelle Ferrell and many more – they were all here in my living room and gave me a wonderful experience! Do I need to say more?

And all because of your Fidelizer PRO so thank`s to you Mr Keetakawee Punpeng for giving me this experience!

Kurt Vallenes

Indeed working well and I pleasantly surprised at how much noise has gone away from the music…

Well done Sir.

Thank you

Lentini Davide

Thanks for getting the program to me so quickly. I have had a few hours with it this this evening & WOW!! what a difference compared to the free version. I’m so glad I upgraded & I will probably go Pro next month when I have the money. Is it correct that I could do that for an extra $30? The bass is deep & tight now & the soundstage is wide & precise. The shear amount of small details i’d never heard before was amazing even though I have a decent system. Thank you for you hard work in creating this program & improving my listening experience by such a large margin :-)


After upgrading to Fidelizer Pro

“Much more subtle changes this time but very nice one’s. The soundstage is fantastic, wide & 3D. Also, vocals are brilliant. Lyrics I could never make out are now clear to me without straining to grasp them. It’s taken the last bit of harshness from the treble & as a result female voices are smooth especially sopranos. I just want to keep playing my music now!! :)


Michael Ashton (JPLAY)

thanks so much for generating the program so quickly this (my) morning. I downloaded in the meanwhile and did a bit of listening – so far: absolutely great! Even more transparency/veil off/details compared to the trial version and it feels like having a more precise low end. I never got close with my high-end CD player to what a properly setup and fidelized PC via DAC is capable of doing.  Late night listening will follow, the first glimpse is great!

Michael Sauter

Hi mr. Windows X,

I installed your software on my dedicated audio player. The system was already tuned by the Highend Audio Pc app from Audiophil together with Jplay 6 beta running on windows server 2012. Even on this fully tweaked system there was a remarkable improvement of the placements of voices and instruments after running Fidelizer, so the two programs probably perform different tweaks

Mike Agsteribbe (JPLAY/Audiophile Optimizer)

After several hours of using Pro, I’m very pleased with the purchase and am happy funding your endeavor.

I’m using an Apple Mac mini running Bootcamp, Windows 8 and JRiver Media Center in a headless configuration using JRemote.

Mike Bieda

Your software is fantastic! I had been having trouble [I thought] with my Yulong DA8 DAC: on certain tracks and especially on Sarah MacLachlan’s “Angel”; there was a terrible distortion on vocal peaks. I discovered through research that this might be caused by Windows resource allocation, which my installation of Fidelizer Pro has decisively proven. Not only has this distortion been completely eradicated, but the digital side of my system sounds far better than it ever had before

Norm Armstrong

Norman Armstrong

It works really well. Bravo!


Paolo Patara

Thanks for the 6.1 update to Fidelizer Pro. I tried this tonight and I am very impressed with the additional texture and detail this now brings to instruments. I have a JPLAY control/audio pc set-up and I have posted my impressions on the JPLAY forum (I am rocketiii).

Many thanks for your work,

Paul Fuller (JPLAY)

thank you very much for your quick response. I have just installed the Fidelizer Pro and it works just as expected. I am really impressed, how much difference the Fidelizer makes to digital audio. I always disliked the “digital sound” with its glare, graininess and simply sterile artificial sound. I even changed my music selection according to avoid the bad effects as much as possible. No more great female singers and so, because digital it just made it impossible to hear. But NOW THE MUSIC HAS RETURNED and I can listen to what I want and not what digital can reproduce without causing just pain in my ear.

I was using a pretty expensive vinyl record based LINN hifi system (with Linn LP12 record player), before having switched to digital and always missed something. Well, it’s here again, sounding like a very very good analogue recording to my ears – thank to Fidelizer Pro!

Peter Böhm

I am enjoying listening with Fidelizer Pro operating.  I don’t find I can definitely identify specific improvements but feel over all the sound is clearer and allows bigger stage with more precise instrument location.  Perhaps the bass is a bit tighter but the difficulty/delay of going back and forth with and without fidelizer running on my server limits precise comparison.



I had already installed AO1.31b9, JPlay 6, and the latest Minimserver and streamer on my W2012r2 server.  It sounded quite good.  But then installing this latest Fidelizer pro brought it up a whole level in clarity, imaging and depth.  Beautiful!

Richard Gerber (JPLAY/Audiophile Optimizer)

Hi Keetakawee,

Have been testing Fidelizer pro now for two days and I can only say that I am impressed. I am mainly listening through a highly revealing headphone (audeze lcd) system, which was already sounding pretty good, but your software gave a very worthwile improvement. Tonal colors are more natural, the last bit of harshness has dissapeared and it is now very easy to become completely immersed in the musical event. Just beautiful and often breathtaking

Thank you!

My system:
Zodiac gold dac with voltikus ps
audeze lcd-2 headphones
cardas golden cross ic
nbs and lessloss power cords
violectric V200 headamp
jplay 6



Hi Keerakawee,
Just want to tell you that I am more and more impressed by the results of Fidelizer pro…music sounds so much more like the real thing. It is like going from an average turntable to a real good one. You don’t have to have golden ears to notice the improvements and there are no trade-offs at all. I am very impressed!
regards, Robert

Robert van Velzen (JPLAY)

Thank you very much! Now my CyberLink Power 14 -player plays like never before.


Slawomir Maliszewski

Excellent upgrade on your freebie! on mini 8 VHD of AOed Win2Go Server 2012 R2 Essentials OS bootloaded into RAM, player Lekt.exe out through RME HDSPe card. More detail, dynamics, everything – far exceeded my expectations of what is possible from red book.

Stephen Dengel (Audiophile Optimizer)

After the trial, the better it sounds Deezer is essentially similar to rip the CD, then listen with jriver + Fidelizer yet. (But do not always listen to music with hi-res File I) autonomous Fidelizer Pro worth it. Works like to change my wiring, cable yet some nice lines.

Surawit Jaruwanchai

Dear Mr. Punpeng,

I just had to write and tell you how thrilled I am with your new Fidelizer Pro.

Not only does it provide some of the best sound I’ve ever gotten out of my system, but it does it in such a trouble free manner.

I’ve used many types of software to improve the sound of my setup, but too often they are like a fine race car; they’re temperamental and require a lot of care and maintenance to do what they do.

Your Fidelizer Pro just does what it’s supposed to do quietly and effectively, and it does it so WELL! Not only that, but I can use it to improve all my sound sources and not just my CD collection.

I’ve used your free version for several years and as good as it was, this is a huge step up in sound quality.

I’m a musician and could try to go into great detail about sound stage, imaging etc., but the fact is if I can’t just relax and enjoy the music then what’s the point?

Thanks to you and the good folks at JPLAY, I’m enjoying my music like never before.

A brilliant effort. Thank you for making it available. I look forward to your future developments and wish you all success.

Wes Bush

Wesley Bush (JPLAY)

I’m enjoying the software very much. Previously I had used Free Fidelizer in addition to running my PC with Win8 in safe mode and doing much of the service closures myself. I tried this same path with Fidelizer Pro but found that starting windows in normal mode and letting Fidelizer Pro do all of the adjusting by itself actually sounded better. I went back and forth several times to come to this conclusion, although I heard it right away the first time I listened.

I am listening through a PS Audio DS DAC and getting wonderful sound.

Will Glenn

William Glenn


If you’re using upgraded Fidelizer software and currently enjoying good music, please share your story with us. If you have any trouble using Fidelizer, please do not hesitate to contact us and resolve the problem together.