First I would like to take a second to thank everyone here for a wonderful education that you have provided me in the area of home theater. This is simply the best resource available and over the past several months has provided a wealth of free insight. Now my question - I currently have a shiva built to the Adire EBS specs powered via a PE 250 plate amp with gain set to 12 o'clock position. The voice coils are also wired in a 4 ohm config. I have calibrated to mains (-3dB)through my receiver via a RS SPL meter. My problem is it recently began bottoming out to several demanding bass sections on DVD. This is occurring on far from reference levels with my HK 525 volume set to -30 in a huge room (27' x 33' basement HT). I haven't noticed a problem other than the when the driver is really being called on(i.e. music playback is fine). Also, when I press the driver in manually I can reproduce the "metallic clanking" noise that I am referring to as bottoming out. Anyone with any ideas? I thank you in advance for any opinions as to how I can bring my baby back to health.