I am trying to see if I understand the spec sheets on the SVS web site please tell me if I am reading them correctly!! @ 20Hz the 25-31PC+(tuned to 20Hz)will have 2to3db less output then the 20-39PC+(tuned at the default 20Hz.)Is this correct? @ 25Hz the 25-31PC+(tuned to 20Hz)will have about the same output as the 20-39PC+(tuned at the default 20Hz) ?? @ 25Hz the 25-31PC+(tuned at default 25Hz) will have 3db more output then the 20-39PC+(tuned to the default 20Hz)? So if I buy a 25-31PC+ and decide later that I want to tune it to 20Hz. I will only be out about 2to3 db's at 20Hz??? please let me know if this is right!!! Thanks for your help!!