Pyle 6.5 Inch Wall Mount Waterproof Speaker System for Indoor or Outdoor Wireless Bluetooth Surround Sound System, White (2 Pack)

Personally, I wouldn't overthink it. You've got power and such near the equipment pad/garage already. I'd get something like this and just mount em on the back of the garage: https://www.amazon.com/Pyle-Waterproof-Wireless-Bluetooth-Surround/dp/B01954Q4I8?mfadid=adm My pool is arranged about the same as yours, except that's the back of my house rather than garage. I've had a set of those up for about 5 years now, no complaints. Sound quality is solid. Bluetooth is reliable. They've been through countless thunderstorms and a couple hurricanes without issue.