The Full Range Low Level In is for the Preamp Center Channel Output from your receiver. It is for the lower frequencies in the Center Channel. It is
NOT meant for the LFE or Subwoofer.
If you want to do this, hook the speaker wire from the Yamaha Center Channel to the CLR2300's speaker post. Then hook the Center Channel Preamp Output from the Yamaha to the Full Range Low Level In - that is if your Yamaha has the Preamp outputs.
But like GlocksRock says, it really doesn't do a whole lot.
Realize that even when you use a single speaker cable to hook the BP7006s and CLR2300, you are BI-AMPING each of them already.