The Quatros, being #5 in the product line (1's, 2's, 3's, Treos ) followed by the 5A Carbon and Seven Mkll, are also where the powered subwoofers start, having a built in 200w solid state amplifier. The Quatro, as well as the 5 and Seven, require an adjustable crossover, the M5-HP- comes single ended $895, balanced $995 a pair. They are easily adjustable to match the impedance of your amp. Once set, that's it.
The Quatros are fairly easy to set up, yet take some time and effort, hence are not one to just press into service at a moment's notice, or your whim. Another reason why scheduled appointments for a particular piece are important, so the unit is up and running at its best. So do make an appointment and hear what all the recent press is about.