Prior to assembling my Atari 5200 SuperSystem setup, I did a little homework into the infamous 5200 controller issue. Based on the what I heard on The Atari 5200 Podcast and Wired-Up Retro, I decided early on to order the DB9 controller adapter for the 5200 made by AtariAge user ikonsgr (he also sells on ebay but I can't find his ebay link right now).   Atari 5200 Podcast https://theatari5200superpodcast.libsyn.com/episode-1-getting-started-and-new-beginnings