Hmmm. Looks to me that he answered your questions. (Oppo support is pretty good.) You might consult the AVSforum thread on the 980H for lots(!) more discussion.
If you don't already have the Oppo, then another option might be a network media receiver. Netgear makes two that support USB disk drives and can decode (on the audio front) MP3, WAV, FLAC, WMA, and (non-DRM) AAC files. It seems that you can enjoy video and photos with this device as well. However, from what I have read the limiting factor with video is that the wireless protocol it uses may not provide adequate bandwidth for quickly streaming movies from your computer. Probably not a big deal in your case since it sounds like you're only interested in music at this point.
If video is important to you, D-Link makes one that uses a newer, higher-bandwidth protocol (known as 802.11n). The web site mentions that the product has USB inputs, however it only references them within the context of using a flash drive. You'd have to check with the folks D-Link about whether or not the device can access files stored on a USB hard drive. Also note that the D-Link is compatible with newer Microsoft Windows operating systems only.
Both of the Netgear products and the D-Link one have optical and digital coax outputs in addition to analog RCA jacks, should you want to use an outboard DAC.
Finally, here are links and the names of the specific products I've referred to:
1. Netgear (http://netgear.com/Products/Entertainment/DigitalMediaPlayers.aspx):
a. Digital Entertainer EVA 700
b. Digital Entertainer EVA 8000
2. D-Link (http://www.dlink.com/products/category.asp?cid=75&sec=1)
a. Wireless N HD Media Extender DSM7-50
If you are considering this route, take the time to read the consumer feedback for these devices and companies. Both Netgear and D-Link have A'gon-like forums that you can peruse. As I've described it, the media receiver becomes another component in your home entertainment stack. However, my impression is that you'd have to install the software on your computer and configure the wireless portion of the device, even if you never streamed anything to it from your computer. That initial configuration part can be tricky, so my advice would be to do your research before taking the plunge.