I don't like mini-jack adaptor plugs, they are too easily damaged (or, worse, they can damage what they plug into). My solution would be to get a mini-jack to RCA phono plug cable (RCA phono is the type of connector found on almost all modern domestic hi-fi equipment, also called a 'cinch plug' or simply 'phono plug' depending on where in the world you are). Most PA equipment has mono full-size (quarter-inch/6.3mm) jack sockets, so you will need two phono-socket-to-jack plug adaptors. All these things should be easy enough to come by from electronics good stores.