Thanks for your suggestions! Both of those products look like they would do the trick.
From the look of those 2 adapters I would guess that the signal that comes through the iPod dock connection has already been converted from digital to analog (that is unless the adapters have built in D/A converters, which I doubt). That being the case, it doesn't look as though it is possible to run a digital connection from the iPod to a receiver (although maybe it can be done from iTunes on my computer...?).
Thanks again!