It actually sounds beautiful, with woofer and tweeter attached. But i'm
mostly hearing the woofer.

That's good. The box is meant to sound like one speaker. If you
start specifically hearing the tweeter it's probably distorting.

So, is the tweeter probably ok since i tried it with the crossover
connected and no
woofer? It sounded awful that way and at first i thought something had
gotten messed up. But then i decided, maybe without a woofer attached,
the crossover lets some low frequencies into the tweeter and causes those
crackly, hissy noises.

Tweeter alone WILL sound pretty horrible.