I think the ‘warmth’ people attribute to older media has been shown to have to do with processing.

Modern audio has been mastered for loudness, with the corresponding loss of details and instrument separation. Tape media suffers less from this issue, and old vinyl even less so (but not modern releases).

It's an understandable response to the feeling of having lost ‘something’ in the era of digital audio (which is arguably just a matter of processing, not the media itself).