If your mixer only has 1 RCA output you might want to use a pre-amp with the exception the speakers are selfpowered. In that case you might want to buy a new mixer with XLR outputs. I’m guessing they are not selfpowered. If they were, I doubt we would be having this discussion about RCA cables. If the speakers only have one Left or one Right RCA conection per speaker. The speakers are an old antiquated speaker and your still going to need a pre-amp. In that case you’re better off buying new speakers and pre-amp to push them with. Come on guys this is simple stuff. 