Did Fleetwood Mac's "The Chain" blow up my woofer?

System: Ortofon 2M Red > Musical Surrounding Phonomena II > PS Audio Stellar preamp > M700 monoblocks > Buchardt S400 

Phonomena is set to 46db of gain, 200pF capacitive, 50k Ohms resistive

The other day I was playing "The Chain" off of Rumors, and one of the woofers stopped entirely during the bass guitar interlude. It just went completely silent, no pops, crackles or distortion. The tweeter is fine, and I reversed the L and R channels to confirm this problem is in the right woofer. The volume level was a "strong" listening level (30 out of 100 on the Stellar), but not loud. We were still able to converse just fine without raising our voices much at all. I have certainly listened to these speakers much louder with other sources.

I understand the power amps are overkill, but I figured my ears would bleed far before I was in danger of blowing anything up. Was this distortion? Subsonics? Woofer pumping due to poor TT isolation? Or a simple defect in the driver?