70v PA system wiring question--wattage

I've been asked to hook up a couple of extra speakers onto an existing 70v PA system in a hall. Poweramp is a TOA 900 series, rated for 60w (doesn't say RMS or peak), with a current total of 10 speakers. I'll be tapping a speaker each on the far sides of the room for power and add another speaker to the room extensions for a total of 12 speakers--may be bumped to 14 if need be.

Now, the little transformer on the back of the ceiling-mount speaker has one wire for 70v common, and then 5 more for 10/5/2.5/1.25/.625 watts. No markings on the speaker magnet.

I was going to wire it up using the 70v common 5watt wires (12 speakers total 60w amp). Is my reasoning sound (pardon the pun)? Or should I use the 2.5watt wire in case 14 speakers end up being used? thanks.

If the system won't be driven at constant, very high, volumes then the 5 watt tap should be OK even with 14 speakers. You won't lose much volume with the 2.5 watt tap, though, if you want to be very conservative.

thanks for the reply, jay. no loud music, just mainly to amplify the speaker (person, not noise-maker) across the hall/extensions.