@petrockblog Both controllers are connected to one ControlBlock, so 2 NES to one ControlBlock, 2 SNES to the other ControlBlock. I've also tried to change the position: NES top, SNES bottom / SNES top, NES bottom. Also I've tried to connect with only the 2 controllers I wanted to test at a time, so only the SNES testing, then unplug SNES controllers and only the NES controllers testing. (with off/on of the RPi) When using only 2 controllers, it works fine, so I know the controllers are working as they should do... (these are originals, but I don't think that's a case) I hope you can figure it out!

@TMNTturtlguy Effectively i have thought about it and it is a good idea, but i have already one usb port used by my keyboard, another one by my hard disk, and i would like to keep 2 usb ports free. It would let me to eventually connect other devices such as bluetooth guns (to play "time crisis" for instance) or to add 2 more arcade joystick for 4 players game and so on. I could use a usb HUB to do all theses things but i dont want to add too many intermediate electronic composants to the chanel. Either way if it had been the only solution, i will have chosen this method :) And if someone who reads this topics has the same issues that i have encountered, i'm hoping he will follow your advice. That's the easiest way too do. I think. ^^ Thank you for everything my friend. Cheers from France