I associate modem with the internet and cable box with tv services. Amplified splitter works best with your tv box (get it from your cable operator), I think they have the best and sometime it's free. As for internet, maybe you should think about using a router.
I currently have one HD tv set and 3 standard def sets. I have one cable modem. It is currently split in the basement where the cable comes in. I have a 2 way splitter into a 4 way (5 splits). I recently installed another cable line for another modem. This will now require me to purchase another splitter to add the 6th split. While out shopping, a few sales people suggested I get an amplified splitter. Is this a worthwhile purchase or should I just purchase a 3 way and four way? All the tv's look fine now but I will need to add one cable modem line.
Thanks for any help here