AV:Triad Power Supplies
High quality power supplies for classic consoles are very hard to find. While there's plenty of cheap adapters on Amazon and ebay, many are extremely poor quality that will result in video interference, audio hum, or potentially even damage the console itself. Unfortunately, we're also at a point where the original PSUs that shipped with consoles are starting to die and often changing the capacitor inside isn't enough to keep them going. Luckily, a brand of power supplies has been identified that are approved by some of the most discerning eyes in retro gaming development and have even been approved by the MD Fourier team. This page is dedicated to providing links to those PSUs, which currently ship under the brand "Triad".
FirebrandX, along with Ste from HD Retrovision and many others have determined the exact models needed for international PSUs. FirebrandX's website is currently the most up to date and is recommended referencing there for PSU's outside the US: http://www.firebrandx.com/triads.html.
Pigtail Adapters
Before continuing, please note that some model Triad PSUs can connect directly to a console, but others require a short pigtail adapter. These pigtails don't just fit the correct size power jack, they also can reverse polarity and send power and ground through the correct lines. Trying to force a connector to fit, or forgetting to use the pigtail adapter could harm your console! Because of this, it's highly recommended to use a label maker to put a label on pigtail adapters and on the Triads themselves so that you do not accidentally mix them up.
Also, CastleMania Games offers a "Tower of Power" pigtail adapter that can safely supply power to a Genesis, Sega CD and 32x, all at the same time. Simply select which model Genesis you're using from the drop-down menu and you'll get a kit with everything you need: https://castlemaniagames.com/collections/triad/products/rondo-products-tower-con-kit
Why Triad Brand?
While there's likely other PSUs out there that are safe to use, the main reason for recommending Triads is consistent test results. Many people in the retro hardware development scene have been using Triads and they have been consistently good quality with no performance-affecting production changes between batches.