Christopher Plummer

Disney 4K Blu-ray, see caps https://slow.pics/c/hE3HUCdj

Disney 4K Atmos is great, a reference quality track. It's a very slight remix (music seems to be from a better source), but it's completely seamless and faithful to the original, better fidelity than anything since the 1994 30th Anniversary Edition LaserDisc.

All DVDs (and 2010 Blu-ray) sound far worse than the 4K Blu-ray/LaserDisc and have various missing sound cues.

The remastered LaserDisc PCM mono sounds the most untouched and natural of any version. In 2006, Universal made a new HD master used on all subsequent DVD and Blu-ray releases. The Universal 2.0 mono mix may be a new transfer, different source or remix made from stems as the music and effects are at different levels throughout the track when compared to older copies featuring the mono mix. Additionally there is extreme noise reduction with dialogue sounding too clean and hiss being almost gone. Comparing with the 1996 LaserDisc mono clearly shows in all of these moments that the original mono was mixed differently and to serve the jokes.

The older Universal Blu-ray has a yellow cast (error) especially in the 1912 scenes.

Universal 4K Blu-ray - caps. Looks stunning against the horribly neutralized old master. Very glad Deakins supervised the new grade and had Universal restore his color filters.

Universal Blu-ray (included in the 4K edition) has the original 5.1 mix not on the 4K disc 

The original 5.1 surround mix from the 2011 USA BD was included alongside the new Atmos upmix. The compatibility track is a downmix of the Atmos. The Atmos is overall lightly remixed with noticeably more high frequencies rolled-off relative to the old 5.1. I think the 5.1 sounds better. The 5.1 mix from the USA BD was used as it sounds essentially the same as the EUR BD (with some minor loudness differences) while not featuring the dither noise and low frequency noise that the EUR has. Commentaries between the USA UHD and USA BD are the same, with both featuring Dolby Surround metadata

Audio comparison: 5.1 surround

Imprint 4K Blu-ray > UK ICON > Criterion.

Imprint is same master as Criterion but encoded by Fidelity in Motion without Pixelogic’s filtering.
See: https://forum.blu-ray.com/showpost.php?p=23389310&postcount=10  and https://criterionforum.org/forum/viewtopic.php?p=844792#p844792