We are happily married have always talked openly. We both have decided our next sexual experiment. We have had a woman together 4 times in our marriage now we both have decided we want to have a man together.

Gender is the only that will be different. This being the first time with another male I thought that I might get any advice from another married couple that has had the same experience.

I've not have this experience, but have a little advice.

Same rules and same understandings. Make sure all parties know what is going on and what is and isn't allowed. If a line is crossed everything stops. You've proved that you can do this, it is just a different variant of the same theme.

He's going to need to realize that he's going to see another man pleasure his wife, and that might be a little different then two women on him. Just need to make sure that all the ground rules are in place and that everyone abides by them.

Adding a male partner into the mix isn't really any different than adding a female partner into the mix - as the previous answerer noted, the same open, honest PRE-game dialogue is needed. The only thing that can possibly make it different are the sexual orientation of the males in the sexual group and discussions about whom will be having sex with whom (i.e. who is penetrating whom and how) and how everyone will feel about this new addition and possible contingencies.

Have fun!