Does sound travel better at night?

In most cases the improvement comes from the combination of,
"less noisy" & more abundant power supply,
reduced ambient noise,
and our own relaxation.

You are very likely more deaf at night (people consistently do better in hearing tests given prior to confronting noisy traffic, noisy work environments, etc.).
FWIW.

The wine helps.

Definitely better as I stoke more j _ h. PLUS, the wife and kids have retired upstairs and I'm finally alone.

James 50 and Gregm hit the nail on the head. Yes, less ambient noise allows for more detailed sound from your speakers. When I lived in the sierra mountains, the nights were very quiet and my system came alive with inner detail. Now I live in Santa Barbara and the ambient noises at night are no where as quiet, and subsequently, my critical listening sessions have suffered from it.