Caps as high-pass filters


I have been very happy using the high-pass filters on my subwoofers to blend the subs with teh speakers. It works well.

However, in an effort to minimize signal paths, wouldn't it be more efficatious to use a capacitor at speaker level to compliment the low-pass filter characteristics of the sub, bypassing the extra couple of meters of interconnect?

Pre=> amp=> speaker level input of sub with lowpass filter
Pre=> amp=> capacitor=> speaker

Anyone try this before?
If so, how would I figure out the capacitor values for a given slope and frequency?
Suggestions of type and brand of cappacitor?

Thanks for any input!
bignerd100
I think the worst result of passive high-pass filtering is the audibility of the HUGE cap one has to use. If one solves F = 159155/RC for 50 Hz and 8 Ohms, one gets 398µF. Do YOU know of a high-quality 400F cap? I don't. Then, ALL the music reproduced by that speaker will be be going thru that cap, so it MUST be very high in quality or you'll hear the negative effects of it. I removed the inexpensive 470µF high-pass filter from my Eminent Technology 8s because they sounded bad enough for even this tin-eared audiofool to hear.

Active filtering, ie before the amp, is MUCH easier to implement (with a small, great-sounding cap soldered into the amp) and better sounding.
.
Line-level then?
Has anyone tried something like this:
http://www.audioc.com/accessories1/misc/hipass.htm

?