speaking from a cable guy who worked in the headend point of view: yes you can damage components in the rack if the impedance is not correct, it may not happen immediately, but eventually it will happen(i.e. what happened to the ch.63 honey ?) 4 MgHz video (composite) usually operates better at lower impendances though. Dont' know why. Also, tinning some rg6 to cat5 will change the imp. but to what i dont know; time to get out the multimeter.:)