now is where it gets a bit more tricky... the contractor has ran only one wire to the pool

he said i could put multiple speakers out there.. but unless he knows some way to split the power effectively i think it would sound horrible.. any suggestions??
The only way one wire would work, would be a 70v system.
One wire would be mono.
You would need an amp that was compatible with a 70v speaker.
A 70v system doesn't sound that great. It's more for background music; like in a doctors office.
Does he expect to run all the speakers you've linked to from that one wire?
If so, they all need to be 70v speakers, along with the correct amp.
Or are you talking two different areas?