Bryce_H said:
A different solution, which I have used for years to mount speakers (and even my projector) are these: E-Z Mounts
They are basically a large flare white plastic screw (the anchor) that you screw into the drywall using a phillips screwdriver. They have a hole in the center that you screw the provided screw into that then acts as your mount for your speaker. You can buy them in different holding capacities - I typically use the 50 pound one or the 25 pounds. Lowes and Home Depot carry them. Just tell them you are looking for drywall anchors
Just be careful that you do not screw them in too far and strip them out. If you do, they are worthless.
If you want to do it right, take the time to cut out the drywall between the two studs, fasten a piece to wood between them, and replace the drywall that you cut out. If you visit DIY Network's web site, or visit your local Home Depot or Lowes (or other home building supply store), you will find the steps (and possibly lessons) on how to finish drywall.
Plus, while you have the wall open, you may be able to run the wires so they are hidden if they aren't already.
Patching the hole is not that difficult, it just takes time and patience to do it correctly.
-Lou