Any way to do this without an Airport Express?

I want to stream iTunes over my network to a Denon S302 home theater system. I installed EyeConnect on my PowerBook G4 and am able to share my iTunes library with the Denon, but accessing the songs via the Denon's GUI is slow and clumsy and not what I had in mind. I want to use the PowerBook to stream 'to' the Denon, not for the Denon to 'pull' the songs from the PowerBook.

I realize that I could use an Airport Express, but it just seems unnecessary, considering the Denon S302 has an Ethernet port. Is there a way to direct iTunes to stream via the Ethernet port, and not via the mac's own audio output? I can't imagine that there's not a way to preference the mac's audio output, but after searching high and low I haven't found the solution yet.

Any ideas anyone?

Thanks in advance.