There was much controversy on the SP-9 with conflicting reviews when new. I auditioned one from a dealer and thought it sounded wonderful. The one I bought was sealed in the box and did not sound nearly as good, so I returned it.
I never followed up on differences between different ARC versions but my recommendation would be never buy a SP-9 without a trial audition in your system.
I never followed up on differences between different ARC versions but my recommendation would be never buy a SP-9 without a trial audition in your system.