For classic movie buffs, sites like Internet Archive host films that are legally free to download, some of which have been remastered for 5.1.

If you want to push your speakers to the limit, these "hot" titles are legendary for their sound design:

A masterclass in directional audio and roaring engines.

Incredible atmospheric 5.1 mixing that makes your room feel massive.

Apps like Kanopy or Hoopla allow you to stream high-quality movies for free using just your local library card. Setting Up Your System for "Hot" Audio To ensure your download or stream actually plays in 5.1: