I will say there is a big difference. Ok, fine, I havent heard the 1500, but I had 100 before, and have 150 and 1100 now. I guess 150/1500 are quite similar. One thing is, theres loads of 100's almost everywhere, while the 150/1500 are more rare. If u like 100, u will love 150/1500. It sure is, and sounds like a bigger 100, but theres more to it than just bigger. With its 15'' bass and 360 degrees tophat supertweeter, and slightly different mid/tweets, it sounds not only more powerful/mighty but also much more refined. Big HPM's are expensive here in Norway, so 1000 $ is like a run-and-buy price for us here.