I have been using Roon for a little while. I have a library made up from various sources that contains loads of random music. I have been scanning a CD collection however that I built together with my wife. When I am done, it will be around 500 albums. I am about half way through and last night, I put what I have done on its own disk and have that as my only library at the moment. I have turned off streaming services and have had the radio function on and its been a great experience reminiscing!
Is there a way to reintroduce the bigger library but have these CD’s ring-fenced as its own sub library so that I can sit my wife and remind ourselves that we were cool 30 years ago!
I don’t think so as Roon Radio is designed as a tool to (also) discover new music.
It will likely only do that if you manually disable all other possible sources for audio you may have configured (other storage locations and streaming services). The only quick setting is to restrict radio to your library but your library still contains local tracks from all your configured storage locations and streaming content you may have added to your library.
Use shuffle instead. You may need to customize playback options in Roon’s Settings (cogwheel) to have shuffle available wherever you need it. Note: The playback queue has a 5000 track limit IIRC.