Theoretically, running your audio over USB from a computer will give you better results than using a Sonos or Nuvo system, but on most systems, you are not going to notice the difference. If you are looking for both convenience AND quality, I would suggest using the Sonos CONNECT (the one with a digital output! Formally called the ZP90) and running the digital output from that into the DAC of your choice. Personally, I REALLY like the Parasound ZDAC at about $475 MSRP, EXCELLENT sound for the money! Once you plug everything in and select the proper input on the DAC, you never have to touch it again...simply select your music from the Sonos (or Nuvo) app, and put your Onkyo on the corresponding analog input that the DAC is plugged into, and enjoy!
Also, I second Al's opinion that Wifi should be avoided. If you can't run an actual Cat5 or Cat6 cable through your home, look at using an Ethernet over Powerline adaptor, or use a MOCA (Multimedia over Coax) adaptor to get a hardwired connection to your equipment. It will be FAR more stable than a wireless link!
Good luck and happy listening!