differential versus common-mode noise?

Thx Steve

Thanks Steve. I'm in my 60's and not tech savvy.
So far I don't use cable TV or internet for
music. Will look into.

Thanks Al and Steve.
I take away that both common and diff noise emanate; therefore common and differential noise isolation is required to properly isolate digital components?
Which noise from the incoming ac line is most disturbing to the digital circuits; ie incites noise within my combination CD/DVD, SACD player-a Lexicon RT 20 from about 2006?

Thanks Steve. I recognize and appreciate the value of the units suggested. However they are a much bigger investment than I'm able to make.Your thoughtful consideration of my question is much appreciated. I feel you are an exceptional asset to those of us posting here. Top of mind for me.