re: crossovers, here's why i am especially fond of the marchand xm-9L. besides being transparent, the feature of its "damping" wolume pot at the x-over frequency, as well as low-pass & hi-pass pots, makes it much easier to get your monitors to blend effectively w/the subs. and, i also use a 12-band graphic equalizer w/spectrum analyzer & mic, to make sure the pots are set at the proper position.
when i was running my electrocompaniet amps, i had the x-over set at 60hz. flattest response was w/the low-pass set at -6db, the damping pot set at -2db, & the monitors set at flat. that damping pot really makes a difference. i had listened for ~2 months w/my new monitors, before i pulled out the equalizer - the setting was the same for low & hi-pass, but the damping pot was also set at flat. while i enjoyed the sound, there was something that just wasn't quite right - a bit of congestion, & the soundstage wasn't as stable as i felt it should be. well, the eq showed me the damping pot needed to be backed off to -2db. it was really amazing how everything jelled. more detail, better imaging... just from this li'l -2db tweak...
now, i am running these tiny hotted-up asl wave-8's i got. well, i couldn't use 'em at all in my large room, w/my 89db-efficient speakers - even w/a 60hz cross to subs, these baby amps yust couldn't cut it. switching out the 60hz module for a 100hz module made things listenable. 125hz is even better. having a pair of subs, flanking the monitors (set-up for best soundstage, not highest output), with 24db/octave slopes, means no disconnect between sub & monitor, even at an x-over point as high as 125hz. and, the larger vmps' can put out plenty of spl's, even when out in the room.
anyway, w/the asl toob mono's, & a different x-over point, it was time to pull out the eq again. i'd been enjoying them for about two weeks, but i knew the system needed to be dialed in again. now, to get the best response, i have the low pass at -6db, the damping pot reduced as far as it will go, which is about -5db (i'm guessing, the scale only reads to -4db), and the hi-pass at -3db. it took me ~45 minutes of futzing to get this set-up properly. 1st time, it only took 5 minutes. nothing like 45 minutes of decent-volume pink noise to get the houshold pissed-off at ya!
the next morning at work, i got a call from the wife: "i dunno what ya did last nite, but, man does it sound awsome in here, now!"
well, the ec's are packed up, to go to the ups drop-off today, the tri-tube mesa baron amp was shipped out to me yesterday... next week i wil find out what *real* tube amplification sounds like!
and, likely, x-over point will get dropped back down to 60-80hz, and the eq/spectrum analyzer will get pulled out again... as it will, when the criterion's show up!