I don't know what you are looking for exactly, buddy, but the crossfeed is just that, a delay in the signal to be introduced in the other channel, on minor, or major degree, bepending on the size of room, or physicla separation of instruments you are looking for or want to hear, and that is what physically happen in real life.
The crossfeed that you could find in any headphone amp, do exactly this, delay one signal and introduce it in the other channel, in some cases correcting some impedance issues between the source and amp, there is absolutelly no other way of creating this effect, after the recording is already done, even with the binaural recordings what happen is exactly the same, but just that the effect is "naturally" introduced before the recording is made, instead of creating the effect after the recording is made...
Good luck looking for this effect you are trying to find, but after getting it, don't forget to let us know what it is, and we will try it, and we will let you know how similar it is from the ones we are using (if not the same)
The crossfeed is based is physics laws, and as such it was developed and created by some of our members after a long research, and investigation....