On the wireless option, the Oppo does support DLNA, which is a wireless protocol for streaming music. Your player needs to have the capability to stream to a DLNA device. I am a Windows guy, so cannot help much on DLNA with iTunes and I do not think Audivana supports DLNA. Also, I think DLNA on the Oppo only supports PCM and not DSD, although that should be confirmed.
The problems that people try to address regarding usb are jitter (timing errors), poorly formed waveforms and electrical noise from the PC. Async usb greatly helps with the timing issues, as Doogie pointed out. The timing and waveform issues are often addressed by the usb to s/pdif converters, although s/pdif has issues of its own. The wireless solution completely isolates the PC from the Oppo, so you do not have to worry about the electric issues. Some people are also concerned about RF noise effecting the usb input. The quality of the 5V signal on the usb is also an issue. I am not sure if the Oppo uses the usb 5V signal or not.
As Pkoegz says, most of these effects are second or third order once you get things set up correctly, unless you have a very highly resolving system which usually costs a lot.
The problems that people try to address regarding usb are jitter (timing errors), poorly formed waveforms and electrical noise from the PC. Async usb greatly helps with the timing issues, as Doogie pointed out. The timing and waveform issues are often addressed by the usb to s/pdif converters, although s/pdif has issues of its own. The wireless solution completely isolates the PC from the Oppo, so you do not have to worry about the electric issues. Some people are also concerned about RF noise effecting the usb input. The quality of the 5V signal on the usb is also an issue. I am not sure if the Oppo uses the usb 5V signal or not.
As Pkoegz says, most of these effects are second or third order once you get things set up correctly, unless you have a very highly resolving system which usually costs a lot.