The year 2015 is significant. This was the peak of the "Loudness War" recession. Mastering in 2015 for a pop star of Adele's magnitude meant dynamic range compression was applied heavily for radio. However, mastering engineers often leave the CD Deluxe Edition slightly less limited than the streaming versions.

. Audiophiles specifically target this edition for the bonus tracks, which were not available on streaming platforms like for several years after the initial release. for the bonus tracks or where to find current listings for the physical CD?

Audiophile Deep Dive: Why the 2015 Target Deluxe Edition of Adele’s 25 (FLAC) Is the Ultimate Digital Version