Bought one from a seller on US Audio Mart and it arrived in great condition. Installed it by plugging the RCA wire from the output of my preamp into the Input connectors of the KAB and then the Output of the KAB into my amplifier. I still have woofer pumping. Tested on 3 LPs, all of them with a slight warp. Would it solely work on pancake-flat LPs or should I no longer have any pumping whatsoever? Occasionally, I have a loud THUMP out of nowhere.