How are your Quad rears today? Take some time to make sure the loudspeakers are at least 2 feet from the rear wall & that the outer ends are angled (see drawing below) toward you. This positioning will give smoother bass response in the two octaves from 60Hz-240Hz & better high frequencies, at least on axis. The sound stage between the Quads should be better defined too.

All right then, what about the front of the esl? I like a near field listening position for two reasons: 1) the closer one is to the loudspeaker the less the room intrudes and, 2) the Quad is virtually seamless enabling the listener to move surprisingly close to the speaker's grill. Taking into account the narrow sweet spot (caused by mediocre high frequency dispersion), I prefer 7 feet from the center of each esl to the listener. This dimension is based on a stereo spread of about 6' or so from treble panel to treble panel. I hope this increases the boundaries of Peter Walker's famous "window on the orchestra" for you.