You can save the money from the USB display. Just enable screen sharing and use another Mac or PC (with free TightVNC) or iPad with VNC viewer to control the Mini. When you have to. You can use the free Remote app to control playback on iTunes.
In fact, I'd try not to use any other devices on USB if you are using USB to transmit audio. Keep the audio files on the network or use a thunderbolt or FireWire HDD for storage.
I'd recommend the iFi iUSB to clean up the USB power. Using another USB-SPDIF device will in all likelihood remove the ability of the Oppo 105D to play back DSD files over USB.
So with the cost savings maybe you can do both :)
In fact, I'd try not to use any other devices on USB if you are using USB to transmit audio. Keep the audio files on the network or use a thunderbolt or FireWire HDD for storage.
I'd recommend the iFi iUSB to clean up the USB power. Using another USB-SPDIF device will in all likelihood remove the ability of the Oppo 105D to play back DSD files over USB.
So with the cost savings maybe you can do both :)