To Cnd,

Thank you for your informative post!

The best memory I have is this trio was playing mostly American contemporary folk but might have had some traditional ballads in the mix as well.
No bluegrass or country. Just very folky!
Or at least the music on the cassette was.

I had a listen to the trio you mentioned, where you could hear two songs. I don't know for sure if that was the group or not. If I could hear the female singer singing it might help because I remenber being very in awe of her voice which was kind of a Joan Baez, beautiful crystal clear soprano type voice. I mean, there is only one Joan Baez of course but the female singing just had a similiar type of voice.
I don't think there were any acapella singing but was all vocals and guitar. I have tried looking online for the first group you mentioned "2/3" Home but can not find anything yet.

Still have to look up the other groups on your list.

The only thing I do remember is that they all lived in or near San Diego as someone mentioned that during the show.

Thanks again Cnd for your help!

Lin