Antenna lead voltage question - Sean? Doug? Anyone?

I'm putting some tower speakers on a buddy's boat. The antenna lead out of the HU already is taken (For what, I have no idea). Anyway, I'm working with a JBL 80.4 on this. I've already wired the RCAs. Now I need the signal to turn it on (which usually comes from the power antenna lead). He wanted a kill switch anyway, so that he could choose to turn the tower speakers off (I've got one on my boat and it works great). My question is this: Since the antenna lead already is taken, can I run a hot wire through the "Kill" swith to the "antenna lead" slot on the amp to tell it when to turn on? Are there any voltage issues I need to worry about?

I'm thinking that this would work fine. This wire is solely used to tell the amp when to turn on, so I'm thinking (and hoping) that any ol' 12 volt signal will do the trick. It's the RCAs that will actually be carrying the stereo signal. He'll be able to turn the tower speakers on with the switch as he wishes. Anything I'm missing here???