Commscope 9 port MOCA amplifier setup

Hey guys so i have a quick question. The lines from my street are coming in hot @ +~13DBmv give or take a little bit. Im going to be activating a total of 6 devices on this amplifier including the cable modem on the -6db VOIP output. My question is how can I bring the power levels down and within spec to all devices at the same time. I know I can attenuate the modem and the cable boxes individually but can i add a 2 port splitter with a -7db attenuation outside at the xfinity box on the input side before it goes into the house and then into input on the 9-port amplifier?  Will that attenuate -7db to all output devices connected to the amplifier with the exception of the -6db VOIP port on for the modem? Currently xfinity just replaced the MOCA filter outside in the xfinity box at their last visit before they determined the old PPC EVO1-9-U/U was bad. Will I still need this MOCA filter in place even though I now have a MOCA capable amplifier(CSMAPDU9VPI) ?