Sorry, I forgot that you can't shut the Subsonic Filter off. Assuming you have the most up to date firmware: http://velodyne.com/support/software-updates
...set the Subsonic Frequency to the lowest setting available, (5 Hz.) Set the slope to the shallowest slope available, (6, which means the filter is at 6 dB/octave.) These setting will ensure that the Subsonic filter has as little impact as possible.
See the graph in this document: SMS 2point1point3 Release Notes.pdf 85k .pdf file
i think this is the best i can do, until i can get some acoustic panels...