i dunno how well the low-pass filters would work for subs - seems too much like a hit-or-miss proposition. re: aci's hi-pass filters, according to aci, they are resistively loaded, so i dunno whether or not they use capacitors, or only resistors. i'm sure a fone call would get the answer. and, they seem like a good way to get a blend w/monitors that would otherwise be run full range, when using active powered subs, that have wariable wolume & x-over frequencies. i am considering trying a pair myself, to relieve my proac ref-8-sigs from the stress of those lowest frequencies, when used w/a pair of yamaha yst-305 subs...
doug s.