An amplifier can have a high damping factor but length of cable run and wire gauge can easily knock it down which lessens the amount of control the amp has overs the drivers, mainly the woofers. Crown Audio used to include a chart in its owner manuals for determining what gauge wire needed to be used for a given run length to maintain the damping factor of its amps. Here is a good explanation of damping factor and how it influences speaker performance: http://www.crownaudio.com/media/pdf/amps/damping_factor.pdf A factor of 640 is good, but even less expensive pro and consumer amps can have a higher measured damping factor. An interesting topic would be how exotic speaker cable construction influences damping factor and subsequent driver control.
The link doesn’t seem to work, so you can google “understanding damping factor” and the top link will be to the pdf.