cheap option
A friend of mine had this same problem , and so I came up with this quick and dirty solution for him. it's a pretty cheap solution but requires 18 rca cables all told, which kinda sucks.
Anyway if you want to try, what you do is buy two of these (link below). Run 3 rca from the SACD player to input 1, and 3 rca from the DVD-A player to input 2, then repeat with the 2nd unit, then run 3 rca out from each switcher to the receiver, then all you have to do is click the two input 1's for SACD, or the two input 2's for DVD-A.
switch