Woops, just read thru to the bottom of the thread after I wrote this & noticed that you indeed acquired some Quads. Maybe the content below will give you some slight ideas for tuning.
My experience is not with the 989s; I owned & loved my USA Monitors for a long time. I’d assume there is enough similarity that my experience has some relevance. First, to mention that I don’t recall ever being impressed by the sound from Quads as heard in a showroom or at an audio show as much as when heard in someone’s home. Maybe this had to do with the size of the rooms, lack of attention to detail, or use of non-compatible electronics. But Quads certainly have the potential for some serious musical magic.
Setup to me was much easier than with moving coil speakers. The Quads like breathing room with as much space as possible between the wall behind the speakers and the speakers. Side wall distance is less important. As with most speakers be symmetrical with the set up. Try damping some or all of the area of the wall behind the speakers that that rear of the Quads direct sound to. Try damping the first side reflection points. I used Sonex for damping. The Monitors benefited greatly from the use of a quality speaker stand. I know the 989s differ, though I think there are some after market stands which might be worth experimented with.
My experience is not with the 989s; I owned & loved my USA Monitors for a long time. I’d assume there is enough similarity that my experience has some relevance. First, to mention that I don’t recall ever being impressed by the sound from Quads as heard in a showroom or at an audio show as much as when heard in someone’s home. Maybe this had to do with the size of the rooms, lack of attention to detail, or use of non-compatible electronics. But Quads certainly have the potential for some serious musical magic.
Setup to me was much easier than with moving coil speakers. The Quads like breathing room with as much space as possible between the wall behind the speakers and the speakers. Side wall distance is less important. As with most speakers be symmetrical with the set up. Try damping some or all of the area of the wall behind the speakers that that rear of the Quads direct sound to. Try damping the first side reflection points. I used Sonex for damping. The Monitors benefited greatly from the use of a quality speaker stand. I know the 989s differ, though I think there are some after market stands which might be worth experimented with.