I'd recommend
'Pi' (Darren Aronofsky)
'Paris, Texas' (Wim Wenders)
'Children of Men' (Alfonso Cuaron)
The BBC Series 'The Life Of Insects'
And my most boring recommendation ever, for sheer filmic 'naturalism', any of Woody Allen's films between 'Annie Hall' (1977) and 'Husbands and Wives' (1992). They're mixed in Mono. Yes, mono.
EDIT:
I also have to add
"Melancholia"
"Jagten"
Both sound designed byt Kristian Eidnes Andersson