Adjust the crossover frequency
Take the equalizer out of the picture for a min. I see you mentioned you changed the crossover... It could actually be the crossover frequency (Hz) you have your speakers set to. If it's set to low, you will be cutting the highs off. Set it too high, and you cut off the lows. If all of the speakers are set incorrectly, it will sound dull, because your not hitting the ranges the speakers were designed for. This is the range that "said" speaker takes over that audio range.
For instance, I have two Klipsch RF-82 II towers, which can handle a full range, so they are set that way. But I have 4 Polk Audio satellite surrounds, which have a higher range, but can't handle the lows. (Little tweeter boxes..) If I set them too low, they sound washed out. If I set them higher (I think around 130-140Hz if I remember correctly) they sing.
The sub I use, Klipsch RW-12D, carries the lower Hz objects with assistance from the RF-82's.
After you do that, you then start to balance your room by adjusting individual speaker output or volume (or EQ), as well as adjust for placement/distance.
If you have the distance settings wrong, your sounds will overlap, enough to muddy the sound, but probably not enough to clearly echo.
It's also a good idea to turn on the tv, find a show where someone is speaking, like the news, and tune your center channel levels to the voices. It won't really be used when listening to most music, but will sound bad when watching tv/ movies if you don't.
I hope that helps.