As a long time owner of the Quatro's they are among the most accurate/bang for the buck speakers out there with their powered bass modules/damping controls and 11 band EQ. Concerning the external X-overs, one just needs to know the input impedance of the amplifier to get a pretty close rolloff that will work in most situations. For those perfectionists, the multimeter and frequency discs are required. As to issues I've encountered, I've had to replace one midrange driver due to a "buzzing" issue at certain frequencies, mainly female vocals and now the other speaker has developed the same issue. The other inconvenience is that the output leads on the external X-over are very short and with my Pass Labs Aleph 3 amp, present a challenge to connecting them to the inputs. I had to get Female to Female RCA couplers to extend the connections to allow the modules to be dressed well clear of the back of the amp and placed on a solid surface(rack shelf). Other than those issues, they are one of the best speakers I currently own and will certainly trounce the Trios but care must be taken in their setup to achieve their full potential.