Hello,
 
    Basically, I'm having a little internal argument with myself about the correct definition of a crossfade is.  I have two ideas of a crossfade, but which is right?
 
A) A slider that goes from -1..1.  When the slider is at 0 both signals are at 1 (full volume).  As you stray from zero in either direction, the corresponding input's (left - less than zero, or right - greater than zero) volume is reduced and the other input's volume stays at a maximum of 1.
 
or
 
B)  You have a slider that goes from 0..1.  The output is equal to Input1 * slider + Input2 * (1-slider)
 
This may sound confusing in writing, as I've written it quickly, but the corresponding diagram might help:
http://defaced.net/buck/misc/xfade.jpg
 
Hopefully someone will know which is correct.  Thanks for any help you can contribute.
 
-Jordan