Bi-wiring in wall, dilemma

[lmwong]

Sorry for the long post...

So we are having our basement renovated and a section will be devoted to a home theater (100" screen, theater seats, 7.1 sound etc). I've been so busy at work and this remodel has come at such a fast pace that I haven't been able to really oversee the details of the construction (it's killing me bc I'm so OCD!).

The components will go in an adjoining storage room so I wanted all the wires through ceiling and behind walls. I called a local installer to run the speaker wire and they were able to squeeze me in due to a cancellation before ceiling drywall went up (existing drywall on walls). Well, they came and left in about an hour and I was thinking to myself, that wasn't very hard was it! A week later I'm thinking about components and realize that the speaker wire for the fronts and center are 2 core instead of the 4 core needed/(wanted?) for bi-wiring my speakers (Polk Monitor 70s and CS2). I never told them I wanted to bi-wire, so my fault.

During our initial discussion over the phone, I said I had speaker wire they can use (monoprice 12G in wall 4 core) but he told me they have to use their own cable for "liability issues". Looks like they used Monster Cable CI Pro 16G (and charged me an arm and leg for) .

I'm thinking about attaching (somehow) my monoprice 4-core cable to the end of the existing front cables in the walls and pulling it through from the other end. Is this hard to do and should I worry about "liability issues"? I hesitate to call the installer back and have him charge me again for running another set of cable through the walls. I read the nice sticky about running wire through walls and it seams easy enough. I also read a thread that bi-wiring is only beneficial if the two cables are separated an inch or two so as not to interfere with each other.

Your collective thoughts are appreciated by this new comer...Thanks.