maybe this info will help :
For those who are interested in knowing the answers to the questions in the original post:
I got my GFP 750 and hooked it up. The HT bypass works great!! You can essentially ignore the "Processor out" connection.
One great thing is that the preamp transforms unbalanced signal into balanced one for output. Very convenient feature. The HT bypass is totally transparent. I don't have to re-adjust the level in my AV processor.
This is a great preamp at the used price. Very pleased to have it now.
This is great explanation. I followed the instruction and connected from Receiver out to GPT-750 "Processor In" and left "Processor Out" open; there is no sound. However, when I connected from Receiver out to GPT-750 "Processor Out" and left "Processor In" open; I got the HT Bypass function. Anyone knows why? Can someone upload a picture of the GTP-750 IC Connection or more detail connection of the GPT-750.