Have CDP with multiple digital inputs. Now what?

I have a Wadia CDP with multiple digital inputs and I'm wondering what I can hook up to it, besides a transport, multi-disc CDP, or DAT. Is it possible to hook up tuners, sat. radio systems, or anything else?
Obviously, you can only hook up a component with digital outputs (such as DVD player). Otherwise, you need to buy an A-D converter. Wadia makes one. I am not sure whether Art DI/O can do the job...
I think Meridian makes a tuner that outputs a digital signal.
DVD player, satellite TV, maybe if your video game system has S/PDIF output? Also consider a computer based media server with digital audio out? Or a DVD/CD megachanger/jukebox. Just about anything you would plug into an outboard DAC you could likely use with this cd player. I wish more players would come with them!