Bi-amping: y-adaptors or two sets of outputs?

Hi I'm new and a bit clueless...In bi-amping how much of an upgrade, if any, would I get if I didn't need to use y-adaptors from my pre to my power amp, and instead just had two sets of outputs on my preamp. I'm considering a new preamp and I'm wondering how important this could be?
I wouldn't compromise with y-adaptors. I would find a pre with 2 sets of outputs.
In practice, "Two sets of outputs on the preamp" consists of a Y-adapter inside the preamp. It would be possible to have two output line drivers (fed incidentally by a Y-adapter), but I doubt very much that such a preamp exists.

Minimum loading of the preamp would be achieved by using one interconnect to the power amps, with the Y-adapter located at the power amps.
What are the best y-adaptors for the job? I'm currently using monster 1000i interconnects with monster ihpy-1f y-adaptors. I think monster describes them as having 3 db loss. Is there anything better?