Hi, after using the M&K K series for a couple of years now i decided to get 3 S-150's, which I have heard many time in the past. To my horror when I put them on on the weekend, they sound awful compared to my dinky K5 & K7!! They sound Ok at higher volumes but when listening at a neigbour friendly level which 90% of the time I can just about make out the dialouge, so I crank the volume a couple of notches and its fine but when something loud happens its too loud, I never had this problem with my K Series. There is more detail but it sounds far away dosen't sound as explosisve as the K5 & K7's, WHY !! Do I need to add a power amp to my system? At the moment I have a Onkyo 898 THX reciever, K4 Tripoles, REL Storm5 Sub and the S-150.