Can streamed Music sound better on a Sunday?

Depending on your type of broadband you have what is called contention rates where the available bandwidth is shared, but in practice this would not affect the streaming quality and the management of the packet delivery and local cashe Would manage this.

You're not crazy Ray, probably just paying attention. That's the way it went with me. People would say their system sounds better late at night when the power is cleaner. Right. Dream on. Until one afternoon I put on a CD that I was used to hearing late at night. I had put it on just to have some background music while the system was warming up. Wasn't even sitting down. Caught me completely off guard. Had to sit down and listen, trying to understand what could be wrong. Played again late that same night, sounded just like it should. 

Odds are that is all that happened. You are listening closely and noticing things. Now the fun part, trying to understand why.

That's the part that will drive you crazy. Not the fact there is a difference you can hear. The Wonderland of stories why.

Bandwidth and error rates are easy enough to look into with apps like speed test and error logs/rates from your broadband modem...  I would guess it is something else like power or RFI issues...  Some devices can be pretty sensitive...  Even power or RFI noise from a neighbor or business might be the issue...  Maxwell, Tesla and Faraday suggest that all things transmit and receive...