Best CDs

I'm new to Audiogon, and know the depth and breadth of the knowledge and experience of the people who post on the Forum, so I apologize for this amateur question.  I'm strictly digital.  I've just upgraded my system with an OPPO 205, Krell Theater 7WD, Krell Foundation 4K, and B & W 804s, 805s, and center speaker.  I've played some CDs (old collection), and they sound awful.  Is there a good brand or brands of CD and/or source that I can rely on for future purchases, or is it more complicated than that.