i own a pair of 1.6s. i would not use a sub for music. the loss of coherence is a problem.>>>
Sounds like you have a problem with your room. I've heard two subs (Vandersteen and REL) match well with the 1.6's. Vandersteen is my top pick after hearing a pair with the 1.6's. But I also heard the Martin Logan Abyss sub with the Martin Logan's and was impressed by it's tightness and speed. It might also be a good match for the Maggies.
If you're having coherence issues with a good sub against different driver types, it's almost always a room/placement problem and in some cases (and expense) can be tuned correctly.
From what I've heard it's unlikely that the new Magnepan sub will be of any use to the 1.6.
Cheers,
Robert