to go furthen into what deftech mentioned, your speakers will need to be configured for bi-amping, that is, a binding post going directly to the high frequency portion (tweeters) and binding posts leading directly to the lows (midrange/woofers) another important thing to consider is the crossover that will be needed for this application, (bear in mind that if your users manual on the speakers says that these speakers can be bi-amped, this wont be a problem. and bi-wired is not the same as bi-amped) if you have no crossover, and hook the onkyo directly to the woofers and the denon to the tweeters, than you will most likely damage or destroy your tweeters once you reach a high volume due to the full range of frequencies your tweeter is now trying to reproduce. if the speaker is not designed for bi-amping, but does have a crossover, which is the norm for most speakers, than chances are this crossover is designed for a single full frequency input and seperates it from there so the highs go where they are supposed to go and equally so for the lows, sending this crossover a signal from the denon and the onkyo and just connecting the wires to the same input on the crossover would defeat the entire purpose of bi-amping.
then there is the issue of matching the volumes of the tweeter and the woofer, tweeters are more sensitve than woofers and therefore will be louder given the same wattage from the source than the woofers will be,
i am a proponet of bi-amping, so much so in fact that my car stereo is tri-amped, a amp for the sub, an amp for the component woofer, and an amp for the tweeter, (i did it that way partly because of the obvious performance increases owed to an amp only amplifying part of the signal, partly because i wanted to see if i had the know how to do all that and have it sound good... i have too much time on my hands)
anyway, if you have any questions i would be glad to answer, and if i am wrong on anything, somebody please set me straight
