Why do Wav and Flac Files Sound Different?

And of course the listeners were unaware of file type and metadata status for each trial, correct? And the tests were randomized to prevent  observer bias? And the results were corroborated across multiple listeners, using multiple trials? And all listeners were unaware of the nature of the changes? And dummy A/B trials with identical files were conducted randomly during resting to create a baseline?

No, not all that was done? Not any of that was done? Because absent that minimal  level of basic care in the testing protocols, this 'study' has zero credibility. It's just poor experimental design. Worse, the authors propose no causality attributable to metadata, no 'how' to account for any statistically meaningful differences.

They don't sound different they're the exact same file when uncompressed. The flacs used to take and still do, a bit more horsepower to decompress but nowadays any modern day computer will do the job properly.

Wav vs Flac

Here is a somewhat more nuanced take on the issue. The author is responding to the article that started this thread.

I should stress here that I am not playing my files off of my computer - merely using the computer to store these files and then burn CD's to them which are then played on a Jay's Audio CDT3 Mk3. I am using a 2 year old Dell. What more interests me is the interaction of the computer buffer and perhaps more specifically the buffer involved in CD burning with the quality of the resulting burned CD.

By the way, whether an improvement or not, the "cover art" file is now deleted by me before copying the downloaded Quobuz .wav files to JRiver. I miss the visual tag of cover art in the JRiver front page, but the text caption is sufficient for locating files.

WAV files are so old that there was never a schema developed for them to hold metadata internally.  FLAC is merely a "container" for the WAV files having more robust places in the design (schema) to hold metadata, things like track name, number, and yes, cover art. Even lowly mp3 files have by design, places to put that data. If your streamer is working right, it will use the metadata but there should not be any sound artifacts from that metadata being present because they are not INSIDE the WAV file that is decoded. Free LOSSLESS Audio Codec is the nature of the beast.  The same can be said for Apple's ALAC. I've encoded wav files as level 8 FLAC (the best compression that can be done and still be lossless when decoded) and level 0 (no mathematical compression at all) and can hear no difference in my headphones. But then I'm 65. Still, by design, these things should have no sonic difference at all. Even whatever chips were in a lowly 1998 PC could handle the decoding without issue, let alone modern, much faster chips in phones, and well-designed streamers. 

A little while ago I downloaded a CD quality CD's worth of music (Sarah Janosz) from Quobuz. Once on my hard drive I deleted the "folder" (image of Janosz) from the list of tracks, uploaded the files to JRiver and was interested to see upon opening the file in JRiver that the "folder" image was still active and came up as the usual jpeg in JRiver where it acted as the visual header for the group of files. It would appear to a layman such as myself that this file is permanently embedded in the download even if "deleted." Any ideas on how to really and truly remove it before burning a CD of the tracks?