I think I'm missing something here (don't be shocked). I thought the 990's remote in/out jacks allowed for direct connections of receivers and emitters (respectively). In my experience, a Pre/Pro or receiver that acts as a "passthrough" for IR signals already supports the necessary bandwidth and voltage specs for the signal (38Khz std, I think). Since a block simply provides the necessary power and distribution, it's superfluous in conjuntion with the 990 unless you're sending the signal through more than one emitter cable.

Anyone know what the manual says?