Products or solutions like Sonos Connect

That is going to at least partially depend on your existing equipment. I can do something like this with my network-connected receiver without adding any additional hardware.

Well then, you'll need to add some kind of media streamer, whether it be Sonos, Western digital, Roku, etc. etc. Your decision will rest primarily on features and how technically adept you are with thing like setting up server software on your main computer. If you just want to play Pandora, and if you don't really care that much about using the tablet pretty much any box will do it, so buy a cheap Roku and enjoy. If you need to access an existing digital library on your PC it's going to be a bit more involved and to be honest I can't offer any suggestions as to the best way. I do most of my media streaming via my Blu Ray player, and don't worry about smartphone/tablet control.