In my initial listening notes, I crossed out Fidelizer and wrote Spatializer instead because the most obvious trait to my ears was how space rendered; and how various instrumental and vocal images placed within it. To me, most computer playback systems sound slightly flat, two-dimensional and lacking in body. The enhancement of depth and the resolution of the complex layering of large-scale orchestral music came off stunning with Fidelizer. Whilst aspects like flow, reduction of hashy treble and quieter backgrounds generally differentiate computers from dedicated disc transports, the latter tend to take the palm in weight, texture and body. If you have retired your silver disc spinner but still have it on hand, do try re-connecting it to your DAC. You might be surprised. Even today I prefer several of my CDs played with a disc transport rather than as files on my computer. But then again, I can't play DSD or 24/96+ on a transport so the argument is rather moot.

I noted how Renaud Garcia-Fons' 5-string upright bass on Silk Moon [16/44.1 FLAC] came across clearer, more articulate and natural with Fidelizer Pro. Derya Tϋrkan's kemence, a bowl-shaped 3-string lute, sounded cleaner and more defined, less wiry and abrasive. The space around both musicians seemed more dimensional and natural but also more vividly charged. I heard similar traits with all recordings regardless of bit depth and sample rate. A favorite well-recorded intimate jazz recording, Holly Cole's take on Tom Waits tunes on Temptation [DSD64 DSF] was vividly life-like and palpable. Essentially her music became clearer, more focused, more real in tone, texture and image definition. Incidentally, do you want texture? Point your browser to Acoustic Sounds and download the DSD of this gem.

The other key trait that impressed me was reduced low-level electronic noise. That's the kind which tends to subtly mask nuances. It's the small stuff that allows for a more intimate immersive experience whereby one's mind is more relaxed and free to follow individual lines and threads in a piece of music, be it Fauré, Fela Kuti or Fishbone. To a lesser extent, I observed greater focus and delineation which again heightened the sense of real people playing music together rather than a slightly hazy simulacrum. Not so well recorded more recent albums like Keith Richards' heavily compressed Crosseyed Heart [16/44.1 FLAC], Father John Misty's deliciously twisted I Love You, Honeybear [16/44.1 FLAC] or Florence + the Machine's Lungs [16/44.1 FLAC] didn't irritate to the same degree or prompt my mind to wander as much. Offering a little more focus, a more realistic portrayal of tone and less hash seemed to reduce my awareness of sonic shortcomings. It allowed me to actually sit through each album and simply enjoy the music. That's a pretty big deal around here.

After a spell I removed Fidelizer Pro and re-installed the free version. While music sounded more transparent, tonally correct and dimensional than not using Fidelizer at all, the Pro version was significantly superior in every way, particularly in overall transparency and in its rendering of space and layering. To my ears, the modest ask of Fidelizer Pro is way out of proportion to its musical benefits. Having said that, I think any Windows computer for music playback would benefit from the free version. According to Keetakawee, "Fidelizer's core optimizations are highly recommended on every Windows PC. It improves audio performance through Windows' core audio technology like raising system audio's thread priority directly along multimedia and OS resource optimizations. They can get it for free with my basic Fidelizer." Just as a building requires a solid foundation, think of Fidelizer as a robust foundation on which to build your music playback. There is very little in our little hobby—Audioquest's Jitterbug comes to mind—that offers so much for so little as does Fidelizer Pro. Heck, I've spent several times that on component upgrades that didn't offer as much. Fidelizer makes file-based playback more enjoyable. Period. But don't take my word for it. Download the free version and try it for yourself. If you don't hear any improvement, no harm done. Warmly recommended.

Quality of owner's manual: Straight forward. You can view it online or, the latest version of Fidelizer includes manual with the download.
Condition of component received: No issues with the software.
Completeness of delivery: No issues. The fully licensed version was emailed within 24 hours
Website comments: Excellent information.
Human interactions: Professional and friendly.
Warranty: License is for a single PC. Full refund if the program does not function on your target machine after trouble shooting and support. Note: There's a freeware version available with limited features.

Fidelizer website