why do my AR9's sound so lousy?

I recently picked up a pair of AR9 LS speakers in good original shape. I refoamed the 8" midrange and the 12" woofers and replaced the 10" woofers with direct fit replacements. Tweeters are original. I put them all back together, hooked them up.... and.... they sound lousy! All drivers are working (putting out sound) but the quality of the sound is very dull and lifeless. For example I have a pair of tiny AR18B's hooked up on the B channel of the same system and they sound 10 times better than the AR9's. Something must not be right here. Nothing is buzzing or rattling or sounds broken, they just sound like a cheap crappy pair of speakers. No treble detail, bass is not that impressive, overall sound kind of harsh but dull and muddy.
. I refoamed the 8" midrange and the 12" woofers and replaced the 10" woofers with direct fit replacements.That might be the clue to your problem. I would let them work a little longer and then take a listen.
Anything out of phase?
Did the replacement 10" speakers have the same parameters? Same impedance? (just because they have the same size, does not mean they are a correct electrical fit)
Then the crossover may have damaged capacitors.
I would start with the crossover..
1) Is any of the wiring done with push on connectors? If so, get rid of them, worst bit of junk afflicting lots of speakers. Solder everything, if you can't, get the best contact enhancer you can lay your hands on and do every connection
2) The capacitor(s) to the tweeter may be old and "lazy". Replace them with your or someone else's favourite flavour of brand
3) It may be as simple as getting the cobwebs out of the tweeter and its part of the crossover. Drive the system as hard as you dare with clean sound with lots of treble content, for hours on end. Personally, I do it with good time rock and roll, where the drummer is hammering the cymbals constantly -- I like Status Quo myself ... :-)

How much power are you driving them with. I have a pair of AR90's and they are very power hungry...

Did they ever sound good? It reminds me of the joke. "Dr. will I be able to play piano after the operation" " I don't know did you play piano before"?
I agree with the notion of possibly using the wrong woofers throwing the crossover off and/or just not being a great driver.
The tweeters are a mystery but have you checked their integrity. You can run a specific frequncy tracked and sweep recording to check out the tweeter function . you will also see where your woofers kick in. BTW it is a great way to break in gear.