Why do Wav and Flac Files Sound Different?

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?

If FLAC levels 0-8 are all lossless, why are there so many FLAC choices, and why would anyone ever use anything but level 8?

Thanks,

aldnorab

@bolong You can have the image "embedded" in each track as FLAC allows it, in fact you can put a different image in each track of a "disc". If you try any tagger (I use Tag Editor) you will see that and you can also delete the image for each track if you want. When you use a program like JRiver, Audirvana, Roon, ..... to play the files they can work in two ways: choosing the "folder / disc" image over the track image or the contrary.

If one the images is missing, they will choose the one that exists. And if there is no one, no image will appear.

Regarding your question: if you burn your CD (physical disc) as a real CD the tracks are transcoded to WAV and the images are not included in the process. 

@aldnorab You are opening another big and old discussion.

On one side, when hard disk space was not such a a commodity as it is today, people tried to reduce the size of the music files as much as possible. That implies the use of algorithms to "fold" them.

But also implies the use of algorithms to "unfold" them just in the fly while or just before being played. This implies the use of processing capacity of the computer ant that means noise.

Again, in the "old" times, this operation could demand a slightly significative "effort" for the computer. Today you can say that this "noise" is absolutely negligible. It will depend on your computer (streamer, server or whatever)

If you are curious, play the same file / track as FLAC level 0 and level 8 and trust your ears: I think you can use any transcoder to do ver both FLAC files.

And my advice: once you have tested this in YOUR equipment and with YOUR ears, forget it: there will always be people saying that they hear the difference in their equipment and there will always be people saying that with the computer of such equipment is "scientifically" imposible to feel any difference.