What do I need to Stream online music?

simple answer:PC>USB cable>DAC>amp>speakers or headphones>Pandora/Tidal or similar music service.There’s a good PC Audio Forum here.Head-Fi.com is also really great for reviews on just about every piece of gear out there for streaming audio.There are also many choices out there now with amps that have the DACS built in like Peachtree Audio.If you look at my headphone rig you will see how it all comes together.Good luck & welcome to streaming audio.

Thank you.  Does sound quality is the same as CD with hi end equipment?      

It is to my ears & I listen a lot.Some people who have golden ears & multi thousand $ systems might say differently.

Sonos Connect has great user interface, and very easy to use and set up. If you use Tidal you might want to add a low cost DAC like Parasound ZDac or Peachtree Dac-Itx. For Spotify or Pandora no additional DAC needed. After that there are many ways to go, but this is a low cost, easy to use, way to start. And if you don't like it, resale on these components will get you all your money back !

Eddy,  Also check out http://www.computeraudiophile.com/ for lots of good information on all things related to streaming.
Dick

Thank you so much for the info.

I'm listening to a tablet hooked up to the aux. on my pre-amp right now. Just need a mini to dual rca cable and you're in.  There are many options to choose from depending on your equipment.

abucktwoeighty brings up a point I didn't think about.Streaming is PC based so all you really need is internet,music service,headphones or powered speakers like the audioengine A2.This is the absolute basic system & although the sound would be a major step up over the computer speakers it would be a long way from what streaming is capable of.