4ohm and 8ohm

Just hook it up to the center channel + and - like any other speaker. YOu may need to adjust the center channel gain vs the fronts since the lower impedence will likely draw more power from the amp.

Is the Marantz rated for 4ohm operation? If so, you'll be fine. You may have to adjust the gain levels though. Sometimes reversing the + and - leads helps also. But to get the best surround sound, the speakers really should be timbre matched.

Thanks, guys!

Face, my Marantz does not seem to have anything written on the back regarding impendance, but I remember when I was buying it, I specifically matched it to the speakers and the speakers are - apparently - 8ohm (at least that's what the B&W manual and the plate on the back of them say). Should I be digging for the manual for the Marantz?

I just wanted to try out the Kef to see if it will "voice match"(meaning, they'll have similar enough reproduction to blend in together) the B&Ws. - Is that what is generally called timbre-matching? (from the little bits of info I dug up online, it is). And is timbre-matching related to impendance? Aside from the power output, which I'm hoping I can negate by adjusting the gains.