Tape outputs are a fixed volume so they will not work. You might be able to wire in another pair but I would think that the output will be compromised and level sets will be different between all three outputs if two are bridged together.
If you are triamping you should be using an active crossover driven from your preamp or a DEQX system or something similar
If you are triamping you should be using an active crossover driven from your preamp or a DEQX system or something similar