Do I really need a crossover when running 2 amps?

Last night I tried running my two Hafler amps bi-amped. One a DH500 to the horns, the other an XL600 to the drivers. I just purchased some inexpensive rca Y connectors. Wanted to see if the sensitivity of these two amps was close. They sure seem to be!
I must say I was floored with the result. Bass was much deeper and the highs much more clearer. I really didn't expect this result. I would think I would of needed a crossover to separate the signal from the preamp and then direct that to each amp. Maybe I do? I am a bit ignorant here.
Can you just split the signal from the preamp and run the output from one amp to the high connectors on the speakers and the output from the other amp to the low connectors on the speaker? I am thinking if I get a crossover, maybe I can get to sound even better.
Not sure I am going to do this, but like to know what I need in case I get the bug. One thing I am aware of is the more power you have the more apt you are to use it. I was listening to concert levels last night. Things where falling off shelves, it really was awesome. I am a bit old for this. I see a hearing aid in my future...

Also, I was thinking of trying silver interconnects, not sure I will be able to track down a silver Y connector, if I decide to keep they way I have setup now.

Anyway, any suggestions or info to set me straight sure be appreciated.