Jay-O: while not as tidy a solution as built-in b.m., you could always buy an
ICBM from Outlaw. And with it, you will know that there will be no low-res digital circuits reducing the resolution of your sacd/dvd-audio signal sources (not that analog b.m. circuitry is 100% perfect either but you see what I mean).
Or, if your speakers are large enough, you could take the advice of a lot of surround music engineers & be part of the lunatic fringe that doesn't use b.m. at all for their surround music.

Since each person's system is different, with yours this could actually sound perfectly fine. Plus no worrying about if crossover slopes are matched so there aren't any sonic "holes" in your music, and the additional distortion that accompanies
any type of b.m. operation. While the receiver's amps will be fully powering all speakers--and as some people warn about--it will reach its limits faster, depending on how loud you listen to your music this may not be a problem (it isn't in mine). And anyway, not all surround titles put low bass in the rear channels or even the front mains. And quite often they don't even use the center channel.
Not to scare anyone but surround music is still a rather new frontier & solid answers aren't always easy to come by. Personally speaking using b.m. with movie sound effects is not a critical thing but with music I don't like hacking up their signals, no matter what type of b.m. system is used.
Speaking of answers (sketchy ones anyway!), I've been playing around with this problem on a system using a Harmon/Kardon AVR630 set at 80Hz and so far just using my own ears, can't distinguish much of any difference between a bass-managed system and a full-range configuration. If anything, the b.m. system sounded slightly boomier because the sub (Velodyne 12") was being burdened with frequencies meant to be in the 5.0 channels. I could eliminate the boominess by adjusting the sub's x-over down to about 50Hz but what about those sounds between 50Hz and 80Hz? From what I can tell, surround music tracks are not being mixed like surround movie soundtracks so this is why I am hesitant to adhere to the HT standard bass-managed/80Hz x-over configuration.
I sure wish the Dolby Corp. guys that have posted here before would say something about this..............
LJ