Bi-Amping without dual pre-amp outs

I own bi-wireable speakers and two power amps. I am splitting the preamp out feed with solid piece "Y" adapters and using both power amps.
It would apear to me that since I'm cutting the line level feed in half that perhaps there is a better way to achieve more resolution. Any experience with bi-amping and/or insights will be greatly appreciated.
Thank you.

Sincerely,

Drewmb1