^ My word, yes. Playing music files off an attached USB hard drive is one of the more common things you'll find 105 owner's doing. You can also stream files from an SMB server or DLNA server set up elsewhere on your house network. The 105 and newer 105D also have an Asynchronous USB DAC Input which you can connect to a computer and play stereo audio into the OPPO from the computer as if it was an external sound card.
There are only 11,670 posts in this thread discussing this stuff, so shouldn't take you THAT long to absorb it all.
There's also a separate thread for the newer 105D (D for "Darbee" video processing) version, and another thread where people are discussing Gapless media file playback and things like CUE files. Just the sort of reading designed for these longer, late Fall and Winter nights.