In addition to Mlsstl's excellent response, you may find the following thread to be of interest. The bottom line: it's very unpredictable.
http://forum.audiogon.com/cgi-bin/fr.pl?htech&1267845685
Regards,
-- Al
http://forum.audiogon.com/cgi-bin/fr.pl?htech&1267845685
Regards,
-- Al