Waves only show support listed for Cubase 6 and up with Waves 9 but I was wondering if anybody is running Waves 9 plugins ok on a Cubase 5.5.3 system?
Waves 9 should work with Cubase 5 since they’re VST3. You can always run the trials that are on the Waves website: Downloads | Waves.
Whether they are supported with Cubase 5 or not would be the question, but I doubt you’ll experience any problems. 