I have a general quesiton regarding the technique of 'cross talk cancellation'.

Most of the work done out there is 'cross talk cancellation for a single listeners with two speakers symmetric to the head/listener'

For example, if someone wants to cancel the cross talk coming from a speaker far away from listener, then what would be the best position of the cancelling speaker? In general, my question is that if the cancelling speaker should be as close as possible to the speaker giving cross talk to get the maximum cancellation? Or could any position help in giving cancellation?

Assuming the room is reflective and not a perfect anechoic chamber.