"Tunable" probably means there is at least one level control on the back of the speaker that controls the volume of the horn/mid/tweet. At the office we have test gear that I run when setting up commercial audio systems - basically, a device "plays" a calibrated sound through the system and a mic hooked to an analyzer shows the response of the system.

In the real world, you can pretty much make the adjustments by ear and it will sound pretty good. For an amplifier, look for one that has an output greater than or equal to half the power handling capacity of the speakers.

__________________
-Evan


Benz Fleet:
1968 UNIMOG 404.114
1998 E300
2008 E63


Non-Benz Fleet:
1992 Aerostar
1993 MR2
2000 F250