The Rythmik Audio plate amps include a ’Delay/Phase" control, providing continuously-variable adjustment of from zero milliseconds delay / zero degrees phase rotation up to 16 milliseconds delay / 180 degrees phase rotation. Such a control makes aligning a sub with a loudspeaker far easier than moving the sub physically. Increasing the amount of time delay / phase rotation does exactly the same thing as does physically moving the sub further away from the loudspeaker. So you can find a good location for a sub in terms of room modes, then use the delay/phase control to align the outputs of the sub and loudspeaker.