duplicate the track so that you have two tracks with the same audio file.
insert a plug-in (e.g. ReaEQ) on the duplicated track.
start playback and switch the tracks alternately to the Exclusive Solo mode (Ctrl+Alt+click the Solo button). Now you will always hear a gap in the sound of the alternating exclusive solo of the two tracks. This is annoying if you want to compare the sound of the tracks. Remove the plug-in and the sound gap disappears with the alternating exclusive solo of the tracks.