reply to HunterZ
Re: [Signals] Just moved and need some advice Updates:
Measured how much cable I'd need in order to run it through the garage; I think I'd need around 60 feet.
Called Comcast to ask about some HD TV channels appearing to be out of service, but it turned out to be my fault for not realizing that I had used a short run of RG-59 to connect the Tivo HD to the 2-way splitter (doh!). Didn't realize that a symptom could be specific channels dropping out while adjacent channels still work fine. Jiggling the cable made them work, but I replaced it with an RG-6 cable with better looking connectors (although it was unfortunately also longer) and the signal on those channels appears to be quite solid now.
While on the phone with Comcast, I also asked about getting a ground block installed at the drop. They put in a request to have someone call me in 4-7 days to schedule a technician visit.
San Jose, CA
Running a new coax from the living room inside the garage is a good idea. However, since the wall is between living space and the garage, it's most likely a firewall (a real fire wall, not a network one). Any hole(s) you poke through that will have to be resealed in a fireproof manner. You'll probably find there's a layer of plywood under the rock on the garage side.
Is there power nearby in the garage where that amp is located? Might I suggest that you hang the SB6120 on the wall next to the amp and run a section of CAT5 along with the coax back to the living room and your router. That way, any splitter installed when Comcast comes to visit will be near your service entrance, and any loses to the modem will be minimized.