We find that the key to surround sound speakers is to have the tweeter angle facing directly at your optimal listening area (i.e, pillow area). In other words, your ears have to be able to see the tweeter, in a manner of speaking.. Figure out the angle of the tweeter and where it's pointing. The actual measurements between the speakers don't matter as much, more of just a guideline. Those tweeter angels, that's what you need to worry about. Hope that helps!
- Brennan, OSD Audio