This is actually a design flaw on the first run of the PMD660 units, and has been corrected on units shipping beginning April 2005. The pad is, in fact, supposed to be approximately 20dB, but for some microphones, this actually attenuates as high as 40dB, leaving little signal left for recording. Per Marantz, this only occurs on certain microphones. This needs to be sent to Marantz directly for adjustment and repair.