i think it is fair to say that the new generation speakers may be slightly better in sound, but i would be reluctant to say "way better".. it goes to figure, with technology advancing like it has, and building materials, and the different products used to make the woofer cones, that the newer lines are more efficeint and more technology sound. but never hearing the 1.5's, i cant say how much better they may be, if at all?
i will say that the QS series are awesome sounding surrounds. they have great envelopement capabilities with movies, and can get plenty loud when listening to sacd's or dvd-a's.
i would suggest for you to upgrade to a receiver with the DTS. to me, that is the BEST sounding format for movies. not to mention, an updated receiver will probably give you much more options with set-up, DSP's, sound adjustment, and crossover settings.
bigjohn
