Hi Rintincop, Please read this thread:
http://www.synthzone.com/ubbs/Forum37/HTML/006415.html

for details on the 'upgraded' woofer that both Beakybird (Larry Levin) and I swapped our stock KP100S woofers for. We both feel it was well worth the extra expense for the added bass response. Before making the modification, I spoke with the President of Motion Sound, who assured me that replacing the speakers would be easy and would not void the warranty on my Motion Sound amp. It took less than 10 minutes to swap both speakers out (basically plug & play and removing cabinet screws). Though I sugguested to him that they should release the KP100S now with the new improved better sounding bass woofer, he advised me that the increased cost would have raised the KP100S' 'price point' too high and affect sales to their target market for that amp. Though I was disappointed to hear him say this, I at least feel greatful now to have a pretty lightweight 'all in one' stereo speaker unit which works well & sounds good for small-medium venues, and with satisfying bass for light acoustic jazz material. - Scott