FLAC Not to mention the fact that almost all music is recorded in .wav files nowadays, and the "lossless" versions are usually just synthetically upscaled for the audiophile crowd.

Yeah, this isn’t how that works.

“Lossless” refers to a mathematical property of the type of compression. If the data can be decompressed to exactly the same bits that went into the compressor then it’s lossless.

You can’t “synthetically upscale” to lossless. You can make a fake lossless file (lossy data converted into a lossless file format) but that serves zero purpose and is more of an issue with shady pirate uploaders.

Lossless means it sounds exactly like the CD copy, should it exist. That’s really all. And you want lossless for any situation where you’ll be converting again before playback. Like, for example, Bluetooth transmission.