What you are asking for is impossible. All your friends will never get good soundstage and centered imagine. The stereo format was not designed for this. That’s its main weakness. Look into multichannel music systems using more than a pair of speakers for that. It goes without saying that the music must be encoded in that particular format. With stereo, the best you can achieve is for two people sitting close together to get decent imaging. The speakers dispersion pattern will dictate how far you can go. DSP systems like BACCH might help. However, the main listening position (MLP) will always be the sweet spot.
Speaker set up for more than 1 person
I have my system set up perfectly for a single person sweet spot. Near field about 9 feet from my speakers. But if I move even slightly off center the soundstage moves and one of the speakers dominates. If I have a couple friends over how can I arrange my speakers so we can all get a good soundstage with centered imaging? Move my speakers closer together?