Good CDs to Test Your System

There aren't any. LP. Records. Now you're talking.

CDs are excellent media. Here are some things which were especially good at revealing what you're asking about:

1. Brian Eno's Apollo CD is excellent. A variety of complicated events, at various points across the left/right soundstage and forward and back are  evident. 

2. Gustav Mahler, Symphony No. 6 with Michael Tilson Thomas & the San Francisco Symphony is also rich in these regards.

3. The Nordic 2L recording of Ives is amazing, too -- and you can find it as a free download. Instruments left, right, forward, back, loud, medium, quiet. Here are some details: https://www.nativedsd.com/catalogue/albums/2lrr1-the-nordic-sound/

There are demonstration discs made by Cheskey Records. 

https://www.amazon.com/Ultimate-Demonstration-Disc-Critical-Listening/dp/B00PUU10BI

there is series called audiophile voices - runs #1-6, done in asia i think

these are compilation discs of tracks by various artists, but the sound quality is truly outstanding

https://store.acousticsounds.com/d/66952?gclid=Cj0KCQjwt4X8BRCPARIsABmcnOrklFz104ZyefDe5PiZR-CI7moZp...

The CDs and vinyls that you enjoy listening to, and listen to frequently, would be the best.