Pav, perhaps you are talking about bi-amp configuration. Mine is not bi-amped neither I have separate subs in the trunk. My sws-8 are the only sub running off PDX-5 sub channel in mono mode (parallel wiring) and if I LPF them 50Hz they are not going to used until bass gets too low. I normally keep them between 110-90Hz. My door coaxials are diamond audio 343i and they are rated as 80Hz-20kHz onwards (as far as I remember) and parallel tweeters are 5k+. As cdgatti said if I setup as per your discussion above I will have a no driver playing 59-200Hz which doesn't sound good option to go for?
2nd question I had is why would I even tweak frequency range, isn't H660 suppose to automatically do it?