Well, I'm surprised at how few members listed classical music. I contend that if you don't use at least some well-recorded classical music for demo purposes, it's hard to pick accurate components. Here are some that sound especially good to me:
Reference Recordings HDCD of Copland (Fanfare for the Common Man, Appalachian Spring, etc.) The slam of the drums on "Fanfare" will bowl you over if your system can reproduce that aspect well. Goosebump music on this disc, at least for me.
Philharmonia Baroque CD of Rameau Orchestral Suites (very realistic sound, with more dynamic drums than the two-SACD by Jordi Savall; Rameau's compositions really stand out compared to the more well-known baroque composers)
Bach organ works by Masaaki Suzuki (96k/24-bit, streamed on Qobuz--these give good soundstaging and bass from the organ pedals)
And for some non-classical picks:
The Fred Hersch Trio Plays... Chesky Records CD--very realistic ambience, natural recording of jazz classics
Michael Stearns Planetary Unfolding (24-bit, 44.1k Qobuz stream) One of the all-time best space music classics, with remarkable 3-D effects as well as much more developed composition than most works in this genre.
I'm actually a fan and practitioner of rock music, but most recordings of it are so compressed and artificial, it's hard for me to think of really good recordings in that genre. I will check out some mentioned above, such as the Unplugged recordings that I haven't listened to in their best versions.
