OK, went back to read your original post again...
And, I don't want to run two set of wires to each speakers.
I see that you want to keep it clean. Like the other posters have described, I do believe there is a 12/2 out there. Just Google for "four conductor speaker wire". I just use two cables. I laid them out where I wanted them and just used little zip ties to bind them neatly to each other. Unless you get close, it looks like a single cable.
Also, I was looking behind the back of the outlaw 990 and the amp 7700 and they both look like female connection in order to connect them together, so that would mean if i want to bi-amp with a y-splitter, i would need one with male connectors on both end. (unless i'm seeing wrong)
But they don't make em that way! Why?
They do normally seem to come as single-male to two-female... You could use something like
this and the just use your normal RCA cables. If you need a specific length, you could make your own if you're into that kind of thing..
And finally, what about an XLR Y-splitter( for using that good balanced circuitry).
I'm sure they're out there somewhere, but I would probably end up making my own. Bluejeanscable will probably make you whatever you want... They might also have the four conductor speaker wire -- have a look over there.
Wouldn't that be better to bi-amp?
Well, as you know, the major benefit to balanced connections is their noise rejection over long distances. I use one for my sub because it's a long run, but I use the unbalanced outs for my main amps because I have more RCA cables, and my amp also has built-in double RCA jacks for bi-amping, so it's more convenient. I love the look and positive fit I get from the XLR connectors, but I don't think it makes much difference sound-wise if your runs are short (I think all my RCA cables are about 1m long). Also, since these amps aren't a truly balanced design (they just add on the extra circuitry to get a balanced connection), it's just more electronics to go through, and some people might think it's another opportunity to screw up the sound. If your runs are short, go with the cables you have handy.
P.S I have read all the pros and the cons about bi-amping and still decided to use up all my channel, so no need to comment about not hearing any discernable difference in sound. Actually Anthem recommends it and i believe in what they say!
Good thinking! Set it up and see if you hear a difference. Good luck!