My house has quite a few outdoor speakers, 6-8 of them. My amp has a "Zone-2" stereo output that I'm planning to drive them with. Each set of speakers has a rotary volume control on a wall in the house nearby.

It's not practical for me to take down and disassemble the speakers to check their ratings. But if I wire them all in parallel, can I simply add 6-ohm resistors to one pole of the amp's Zone-2 speaker terminals before it feeds all the speakers?

I did see this in another post:

Make sure to get appropriate resistors, they will dissipate one fourth of the maximum power your amplifier can output, per channel. If you have 50W per channel your resistors can dissipate up to 12.5W, so you need to get at least this wattage.

It looks like my amp is rated 60 watts per channel, so I'd need 15W resistors. Will this work to protect the amp? I'm not concerned about volume matching between the sets of speakers.