Exactly what are you trying to do? Normally, when you are "biamping" you connect the outputs of your preamp to an active crossover which splits the signal in two at the selected frequency leading to two 2 channel outputs, hi and low frequency.
RCA splitter
Has anyone experience of using an RCA splitter? I’m going to try bi-amping but my preamp has only one set of RCA outputs. I found this https://cdlnz.com/M22F-HRD but don’t know if it’s the best quality splitter available. Any thoughts / reccomendations please?