This review page is supported in part by the sponsors whose ad banners are displayed below By now the time had come to write his own audio playback software. Fortunately Peter had no idea what the coming years would bring in terms of penning countless lines of code, trials, errors and tribulations and zillions of e-mails. The stated goal was feeding a DAC with audio data from a computer as close to perfect 1:1 as possible. A complete no-no was any digital signal manipulation like DSP. At the DAC’s output there was to be no manipulation or filtering, hence a non-oversampling (NOS) DAC was key. To prove that the world had grown small, the converter chosen became a TwinDAC+ purchased from Bert Doppenberg who happens to live a large stone's throw from the Stordiau residence. From this contact a more intense exchange of ideas and visions germinated not least because Mr. Doppenberg is an avid believer in PC audio. It should come as no surprise that more designs from the BD company entered Peter’s listening system—think Orphean hornspeakers with BD15 subs—or that Bert Doppenberg would have and still does act as Peter's audiophile sparring partner. Peter's emerging lines of code were called XXHighEnd which as of our writing was in version 0.9z-7-5, an update already announced as the project is ongoing. We deliberately said project and will get back to that later. For now let’s try to explain what XXHighEnd does. Be warned that XXHighEnd is decidedly not for the faint of heart. It's a far cry from any set'n'forget piece of software. It takes serious effort to get the best from the fruits of Peter Stordiau’s genius. This means that even the software’s author occasionally won't know why something works as it does. It's only with the help of an active online forum that many of the hidden options and features derive full meaning. Audio is no exact science where one algorithm determines good sound. Only humans can assess that quality albeit just on an individual basis. Bringing together numerous interpretations in one forum help us understand music reproduction step by step. In short XXHighEnd is best described as a memory player which only activates/runs relevant parts of the Windows operating system and disables all irrelevant processes to output the best possible signal. From this restriction it becomes clear that Microsoft Windows is a necessity, preferable Win 7 or higher. Now to what goes on when XXHighEnd runs. First you need a ripped music file. The software likes to see all music files under a dedicated root folder and preferably but not necessarily on a different drive than the drive which contains the Windows OS and XXHighEnd software. Under that root folder you can create sub folders for artists and albums filled with ripped tracks. From a Windows point of view a music folder tree could look like H:\music\jazz\Miles Davis\Tutu where the latter folder contains .WAV, .AIFF, .AIFF, .FLAC and/or .MP3 files. Yes, XXHighEnd supports all these formats even when mixed and matched. Once you select a track or album to play from the graphical interface—more on that later—several things happen. Remember how we mentioned this is a memory player? First all disc data must be transferred to memory. Settings and available memory determine the amount of data that's transferred. XXHighEnd only processes WAV files because that's the native Windows format (hence the W in WAV). Any other file format must first be converted to WAV. That's done before the file is transferred to obtain the best-sounding version. Yes, file types and other disc features all play a role in the final sound quality! From this converted disk folder files now get written to memory. This process is applicable for both WAV-converted and native WAV files. A portion of cued-up files remain in memory until their turn comes to play. It only takes a pointer reset at the location of the memory-captured file to tell the software where the file sits. Peter sent us a string or flow chart of how a track from a disk eventually ends up in the DAC: File => FLAC decoded to WAV – HDCD decoding (24/44.1) => intermediate drive => playback drive => memory (Arc Prediction upsampling/filtering +volume setting => kernel buffer (Q1 x Q1F device buffer) => driver device buffer (1ms–16ms) => DAC. One XXHighEnd setting tells it to switch off all unwanted Windows OS features and action strings once playback starts. This mode is called Minimized OS and hands over all available computing resources to XXHighEnd exclusively. Once playback stops, all suspended services restart. But remember that any other application already running on the system is not automatically stopped where it can interfere with playback to cause glitches. Those manifest as noticeable ticks and pops and are of course to be avoided. XXHighEnd is meant to provide glitchless playback at the highest possible quality so don't use your music computer for any other tasks whilst listening.