Hi Stuart,
I thought both DTS and Dolby Digital are supported on optical or coaxial connections? If I'm not lying to you, then, the 5.1 analog outs make sense to me because DVD Audio/SACD don't have more than five audio channels (other than LFE) -- and they'd be the only reason I would connect the receiver and DVD player through analog cables.

Let me know if I misunderstood.
Ananth

Axiom M80Ti, VP150, M3 on walls X 4, M3 ceiling X4, HSU VTF-3 MK3