Not a whole lot. This is a normal thing; the industry doesn't want the possibility of making totally accurate copies of DVD-As or SACDs, so they've done it by forcing decoding in the player. There may or may not be truth in the fact that the optical digital connection is too low bandwidth for the data coming from DVD-As and SACDs. There are some solutions, such as Firewire, but these remain on high end receivers/players for the time being.

I am the Doctor, and THIS... is my SPOON!