DISCUSSION: "It only comes out at night". Does anyone else have this experience!?

Absolutely. My system always sounds better after the sun has gone down. There is less electromagnetic interference and less nasty harmonics on the grid. The Decware guy is right about letting your speakers warm up for a while. Mine always sound better after 20-30 minutes. The same amount of time I let my tube amps warm up.

I am a robot.

Well said Sir Robot 👍

Oh, there is no doubt speakers have to warm up. Both the VC and the surround. It is most obvious to me in my Jeep. First thing in the morning my sub seems basically non-existent. After driving for a bit, ambient temps go up, woofer warms up, BIG difference. 
 

I am a Replicant.

The car at night - Its cooler at night , therefore more oxygen molecules available for combustion . Result more power . Of course turbo charged cars will benefit even more.

Hi-Fi at night. Electro-Magnetic radiation from the sun is shielded by the earth during the night.EM is a known audio noise , that has significant effect on SQ.

I don't buy the AC supply being quieter at night in  a normal residential environment . 

once I lived in a house with such a horrible electrification, that I could only listen to music after midnight.

I highly reccomend to buy a AC iPurifier. It will sound much better!