We are a dealer and have them in our demo vehicle but it isn't really setup for sq. I've actually got a set of the SSMB6 and a set of the SS56.2 sitting in my closet that I'm not using. I've got old school US Amps in my truck right now running a Dynaudio System 360. My problem is that I am wanting to use different crossover points with the set and really don't want to build a passive network. There is alot of adjustability with the SX amps. I was thinking about doing a SX400.2 on the tweeters, one on the midrange, and one on the midbass. But I am undecided. I really love my us amps.
I'm going to be using 2 SX amps, a 900.4, and 700.4, I just got the 700.4 today so I really cant comment on the SQ yet, but as long as it sounds as good as the ZX650.4 I'm replacing it with I'll be happy.