If you have a center channel output and MTM center channel speaker, you really only have two ways to wire them- series and parallel. Parallel will probably make your amp unhappy and series will be OK. You can also make an L-pad for them to drop the level and if you use good resistors, the sound won't suffer. Why can't you decrease the center channel level enough to match the mains?
Funny thing about that. I did that on my Onky TX-905, which was before 5.1 7.1 and all that. So there was no way to level match. I had it hooked up to my remote channel. Maybe I was ahead of my time or was it way behind the times.

If I still had that box I would try again with my Denon.
Like I said on my PC I have some used kenwood JL-801's (they were free). They suck but they are better than my Logitech PC speakers somewhat. One of the tweets are blown. when I got them one of the mids didn't work, but with some simple soldering I fixed the X-Over so at least that works now. I might get some new tweets for them just for the hell of it. Though should I get some el-cheapo's or some badass Scanspeaks or Morel or something.
That is probably what I will do. Than maybe

get some really nice mids then some woofers than build a box around them cause these Kenn's have a pretty shitty enclosure. I have always wanted to do a DIY home speaker.
Alright I'm an audiophile okay like I said I was drunk last night. I can say some crazy **** when I'm drunk. I do know how to start up good threads though.
Dono
I just realized I said I built that center channel for my Denon before but it was for the Onkyo, my bad.