Not true regarding bass managment from analog inputs!
I believe, as I used to sell the Denon 5800 back in '96, that there's probably only one setting for ALL the inputs!
YOu may want to contact Denon and get the manual, or ask em. Or, you can reference the back issues of Stereophile Guide to Home Theater and HT magazine(both did reviews I think), and read about it!(otherwise, you'll have to tinker and find out.
Never the less, I'm familiar with all your gear, and would recommend only running the Dun's full range if you had some kind of "dirrect stereo input/through-put" on your Denon..I don't remember this feature on that unit..it's been too long. Actually, you could run em as "large" for stereo music regardless, if you liked the sound better that way(no sub that is).
However, with HT, you'll STILL HAVE TO CROSS EM OVER AT 80HZ OR WHATEVER, and let a powered sub handle the bass bellow that!
I know there's some Dunlavy onwners who'd dissagree with that recommendation. But I know otherwise! I've sold Dunlavy(and most everything else for that matter) for years, and I know those speakers(which do better for HT full range than MOST passive speakers). You can bottom those SCIVa woofers out, and a stronger pressentation can be had with properly set up POWERED ACTIVE SUBS handling the bass. Even though those speakers have a very fast, tight, controlled sounding bass on their own, DTS/DD still has too much to handle for them correctly.
HOWEVER, I say this for most set-up's. If you listen only at lower levels, and you aren't concerned about ultimate dynamic power and power handling, you might be just fine for your needs running the IV's full range for movies and music both..you'll have to experiment. (JUST REMEMBER the guy a few day's ago who posted who said he blew his JM Utopias woofer's out on the Star Wars dVD!!!....you can't beat powered subs for power handling!)
good luck