Best CDs

I'm new to Audiogon, and know the depth and bredth 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, Kress 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.

You have some fun research ahead of you!  The quick answer is yes - there are labels that manufacture with an emphasis on Audiophile quality; however, availability of specific artists, genre, and recordings on those mediums becomes an issue.  There are plenty Miles Davis remasters from original tape to go around; but if you are a Kenny G fan - you may not be happy with what is available.

To add to the complexity - licensing rights can affect availability by ensuring the product is unavailable on certain labels.  Add to that the fact that the recording engineer has his or her own focus when recording an artist.  Once that recording is completed - there is nothing you can do about the finished product on the master tape which can't be cleaned up after the fact.

As you dive deeper in fine Audiophile equipment specificity of artists may become less important because good equipment has a way of allowing you to appreciate all types of Music.

To get you started on your way with research - here are some websites that have valuable data concerning Audiophile quality:

A center speaker is for home theater,  not exclusively music.  Two good speakers will give you the proper center channel.
You can also search for some "best demo CDs" threads and get a couple to see if how your system sounds playing ones that most agree are well recorded. 
Another source is the dynamic range database
This database works under the assumption that CDs with a wider dynamic range sound better. While generally absolutely true, mastering and other factors also contribute to the overall sound quality. 
You can also experiment by playing high rez recordings thru the usb inputs to the Oppo, if that model has them(the 105D I owned did). Many find that files played sound better than the same music via a spinning mechanical disc. You can rip from CD to digital with free XLD on mac or dbpoweramp on PC. With lossless file format rip(WAV, AIFF, FLAC, etc) the same music sounds better to my ears. That is the first step away from CDs entirely, but that's a WHOLE 'NOTHER conversation...cheers,