Passive Preamp - What makes it work?

I want to try a passive preamp, such as Creek's OBH 12, as an inexpensive pre to replace my current Denon AVR1700. I've read a bunch on here that output levels from the CD and input impedance of the amp are crucial factors. What should I be looking for to see if this is a good idea for my system? Is the goal to make the impedances match, or should one be higher than the other? Also, are there any passive pre's with a home theater passthru?

My system:
Joseph Audio RM22si signatures (86 db sensitivity)
McIntosh MC-2105 amp (input impedance 200k)
Music Hall CD25

Thanks