Now to find a USB A to USB A cable. I can’t believe I don’t have one....I’ve got every other kind of cable in a big box!
Going online (Monoprice and Amazon) I was surprised how much searching I had to do to find one. What’s up with that?
USB A to A cables are rarely used or available because you wouldn't want to have the possibility of connecting two hosts together, both having a +5V power line which could produce damaging results. There are USB A to A Data Transfer cables used to network two computers together via USB, but they also have electronic components inline with the cable.
USB A to B cables are generally used to connect a USB host (computer, streamer, etc.) to a USB peripheral (DAC, printer, etc.).
AFAIK, the Oppo 103 / 103D does not have a USB DAC input that can accept a digital audio stream from a computer or streamer.
A USB DAC input, such as on the Oppo 105 / 105D, uses a USB Type B connector.
The two rear panel USB Type A ports (USB1, USB2) on the Oppo 103 are host ports that can accept mass storage devices (thumb drives, hard drives, SSD drives, etc.) or USB adapters such as a WiFi network adapter.