The demarc/tap goes directly into an amplifier that feeds a 4-way splitter, 3 of the 4 ports go to other buildings on campus. the 4th port is then connected to a 2-way splitter that feeds 2 12-way splitters that then feed the 20 colocated STB's. When first installed 2 years ago we were hitting the STB's with too much forward signal so we had to put in attenuators. We know that the attenuators also effect the return path.
The amplifier has an option for active return path gain(up to 18dbmv) which we will try next and post the results next week.
I have the same provider at our office and since Tuesday our STB has gone down 2db each morning. It started at 60db, went to 58 on Weds, 56 on Thurs, and is at 54 db today. Im hoping its below 50 by Monday 11-4-13.
Thanks for everyones help and useful links