For western classical music, Primophonic has a very large selection, Tidal HiFi service is CD quality or better but with a slightly smaller selection. Between the two, you'll probably find most if not all your CDs available for streaming on-demand.
Classical music on demand?
This may be a dumb question but please humor me. I am now using a Naim Unitiserve as a source and have ripped hundreds of CDs on its hard disc. As an alternative, is there a way to play (stream) high quality music on demand without ripping CDs? I listen mostly to classical music so, for example, could I play or stream a Beethoven or Brahms symphony with a choice of conductors and orchestras on my audio system with audio quality equal to or better than CD without having to download anything—similar to watching an on demand program on television? What software and hardware would I need? Presumably the hardware would need a screen or would use an iPad or similar screen to select the music. I may be behind the times on such technology so again sorry if my questions show this.