One thing I recommend is more than one pair of speakers. Outdoor Speaker Depot sells very good impedance matching stereo volume controls for a very reasonable price, and you can even get these in waterproof boxes that can be mounted on patios, decks, walls, etc. These are great, esp. if your receiver is in the house, or you have more than one set of speakers in the yard.
The advantage of having more than one set of speakers is that you can place them in different parts of the yard so that you never have to turn any one pair up that loud. This minimizes disturbance of the neighbors, but also allows you to have conversations near the speakers, while people in the pool can still hear the music. I have three sets and am working on wiring them all up using one older Onkyo stereo receiver in the pool house. It's dedicated to this task. The individual volume controls are great because they keep the load to the amp reasonable constant, even if one "zone" is much louder than another. The overall setup is nice because all parts of the yard are covered and it's not necessary to turn up the volume to get even coverage.
The advantage of having more than one set of speakers is that you can place them in different parts of the yard so that you never have to turn any one pair up that loud. This minimizes disturbance of the neighbors, but also allows you to have conversations near the speakers, while people in the pool can still hear the music. I have three sets and am working on wiring them all up using one older Onkyo stereo receiver in the pool house. It's dedicated to this task. The individual volume controls are great because they keep the load to the amp reasonable constant, even if one "zone" is much louder than another. The overall setup is nice because all parts of the yard are covered and it's not necessary to turn up the volume to get even coverage.