I purchased a PB 13 ultra about 7 months ago and whilst i could appreciate what it could do as it could go effortlessly low and loud but it didnt have the sound i wanted as i like a lot of punch. I sold it on ebay and lost approx £1000, my own fault i suppose. But i recently bought dual sb12 nsd and whilst running them in i was enjoying them until the sound changed for the worst! I ran rew but couldnt find anything out of the ordinary but i knew it sounded different. Whilst moving the subs around to experiment with room location i noticed a rattling noise coming from one of the subs like a component has come loose. This is disgusting i have given svs £3150 over the last few months and this is what i get. Is the other one going to breakdown in the not so distant future? I only bought svs due to the excellent reviews online but over here in the uk we pay a premium for svs and we buy blind with no 45 day trial period. I put my faith in svs and i was wrong. Sorry for this post but i had to vent my anger somewhere!