It’s pretty hard to give a considered answer, as several of your components are unfamiliar. However, having seen the picture a few thoughts come to mind:-
1. Some sort of room treatment, beyond the cushion behind the speaker (!), might well be beneficial. Sloping ceilings can be a boon or a nightmare, but I wouldn’t know from looking. Possibly some isolating tables/stands for the kit too, as the very attractive ones I see, look like they may be normal furniture.
2. Generally, I tend to favour the ‘source first’ approach, though not as religiously as, say, Linn tend to. Speakers change the sound the most, because they’re transducers, but no speaker can retrieve information that never left the CD or record.
3. As CD is your main source, have you ripped your CD collection or do you replay them ‘live’ as it were? If you still play live, then top-end streaming devices like the Innuos Statement or Linn Klimax new generation DSM might give better results.
I hope that helps a bit.
EDIT: Posting the above without being able to view your kit, I now see you have a streamer. Do you use that over the Meridian CD?