where to start

Instead of being tied down to installed speakers inside the house - if these are all that you mean by a system - I would take a look at play units/playbar and Sub as components from which to build a home audio set up. No Connect or Connect Amp needed in this alternative.

The installed speakers outside the house may be worth pursuing if you like the sound you obtain, and if listening to them is just a matter of wiring an amp to their wires that have been brought inside the house.

Thanks. All the wires come in at the TV input. That is why considering a connect;amp first. I really want to be able to listen outside since I have a nice patio.

Good idea, if you can get one on a returnable basis. Where is the WiFi router? If you can also conveniently wire the Connect Amp to it, you may not need a Sonos Boost. The latter is only needed if no other Sonos unit can be conveniently ethernet wired to the router for the preferred way of WiFi use for Sonos.

For the initial test set up of Connect Amp, there is no need of connecting it to the router or using a Boost.

Thanks for response. The router is about 10 feet away in a closet. I do not think that would work. I was considering betting a boost. I already have a 3.1 and will add others with time. Just trying to figure out the most economical way to get what I need.

Try a Connect Amp on returnable basis then, running on the home WiFi, without either wiring to the router or a Boost. If you like how the music then sounds in the patio, keep it and think of next steps - which will also include trying out the Connect Amp with the installed speakers in each room which can be easily done since all wires come to one place.