I was originally thinking transistors, but they are polarized, are they not?
FETs?
It almost seems it would be easiest to just have a crosspoint capable of > 9v.
ADG5204, ADG5208/5209, ADG5233/5234, ADG5236. But AFAIK they all need dual supplies if you want to switch AC. This could be generated locally with a DC-DC converter though. For DC they go to 40v or some such.
Rob