Amp Cable Modem Question

I was getting some high upstream levels (52-53dbMv) with my cable modem plugged into the passive VOIP connection of my Comcast Amp. I moved the modem over to one of the powered ports and now I get the following power levels (48-49dbMv). Is there any problem with running the cable modem through one of the amps powered lines. As an FYI, this is one of these Commscope Amps that Xfinity installs that provides even output to all sources.