If you don't already have a whole home audio setup Sonos is a little expensive, but great and simple. I have two Sonos amps, one newer style and one older white one. The newer one is hooked up to two Niles rock speakers, and the older one came in a kit with two Sonance speakers (I think the kit goes on sale at Best Buy once a month in the summer, now with the new amp). I also have an older Sonos playbar I picked up from craigslist in a screened in room, I leave out all winter. The Sonos app lets you control all volumes together or independently, and its all over wifi so no dropouts you get from bluetooth. You can leave the amps inside and just run speaker wire outdoor to your speakers. They say the amps can run two or four speakers each. Sonos is also nice because if I have the tv on, the playbar can share the sound back to the other Sonos amps with the sound in sync. If you go the Sonos route definitely check craigslist or Facebook marketplace and you can probably find some good deals on used stuff. I have a decent mix of new and used Sonos gear and I'm yet to have anything fail. All the other speakers just plug into an outlet and connect to wifi to work but aren't waterproof. We keep a small Sonos one in the bathroom on low volume playing the same music as outside. It works with all the popular streaming services as well as local music on your phone or computer, or being fed from another receiver indoors if you have buy the Sonos port. I set the Sonos system up after trying to use a regular amp and speakers for years along with apple airplay one and some 3rd party software. Sonos has made the setup dead simple plus no going inside to turn things on and off. I highly recommend Sonos even though though its a little pricey.