every so often I hear about the concentric woofer/tweeter (coaxial style) drivers that tannoy was famous for. I went to see what tannoy has now in this area and it seems that they offer some studio monitors that have the dual speaker config but I'm confused by the fact that they have a 'super tweeter' that is NOT center-aligned! does this make sense to anyone? isn't the value lost once you take one of the drives off-axis? or, was this concentric stuff mostly just 'marketing' ? I have some conventional tannoys (pbm-8) and I'm curious if its worth it to swap them out and try the new concentrics (my pbm's are a good 10 yrs old now). anyone have any experience to relate on those concentric cone designs?