I think this will come as bad news, but i see no way to get SACD or DVD-A working with your setup (The multi channel version of both).
If you had analog speakers you could go for a analogue 5.1 channel pre-amp, or seperate bass management system to put the output of your 565 into, and also the output of the DVD-A/SACD player.
But as you write you have Meridian DSP speakers i see no solution.
Upgrading the 565 to a 568.2 will give you the option to get a digital MHR input as option. So with a Meridian 598 player you can have DVD-A.

The 2 channel output of DVD-A/SACD could be input on a analogue input of your 565 or 562v3.

You could try a trade in of the 500, 518 and 565 for a 568.2 at a dealer, or see what people pay for it on the 2nd hand market.

Jaco

Sold all M equipment