The thing is analog inputs are needed.
The 568s have, but only 2 and 3 is needed at the moment.
I'm not sure about the order in which the 500 series components were released back then.
But the 561 has plenty of analog inputs.

G61RSL, DSP7200, DSP5200HC
Lumin D2
Akai GX-620, Teac A-3300SX, Nakamichi CR-4A, CR-2A
Oppo BDP-103
Sony PS-X600, Nagaoka MP-110, Denon DL-103R
NuPrime STA-9, Elac BS 63
PS Audio PP10