I just built myself a 4 players adapter to use with my A600, using the guide from here: http://aminet.net/package/docs/misc/FourPlayerGames_EN
I tested it with WHDLOAD versions of Dynablaster and Great Courts 2, and with ADF version of Max Rally.
In none of the games the joysticks 3 and 4 worked at all. No response from none of them (Well, with Max Rally I need to at least press the button to "confirm" the controller and I couldn't. The other 2 games I didn't had response from either directions or fire button)
I tested the connections of the adapter with a multimeter, they are all ok, so I suspect of a faulty paralell port (Never used it on this system).
Is there anyway I can test it? Any other tips/suggestions?