Don't forget we need to be able to adjust the delay for both left and right hand drive vehicles (Right hand drive means the right channel needs the delay relative to the left, and Left hand drive means the opposite (left channel is delayed).

The UI could allow you to specify the delay as either:
A positive or negative value (time & distance) relative to a fixed channel (e.g. left) .

Or you input a positive delay value (by twiddling the knob or whatever) and then you indicate which channel the delay is relative to (left or right).

[and a nice touch would be that if the delay value goes negative, you could show the absolute 'delay' number but change the field showing whether the delay is relative to left or right channel to the other channel from the one currently in it).

Also, bear in mind that some folks use their empegs at home and in the car, so it would be nice (but essential to have settable delays for both home and in car use.

Also instead of using terms like 'Left hand drive' or 'Right hand drive' it might be better to allow the user to simply indicate if the listener is left or right of the (assumed) stereo centre line, and go from there. As terms like left hand drive have no meaning in a empeg used inside the house.