Sorry I have been away from the forum for a while. I haven't had a good reason to post until now. I wanted to check if this LFM-1 resonance was a common problem. I really cannot listen to anything loud without the rattle coming in and I don't think it is the glass.
I ordered an auralex gramma isolator for the sub. I noticed that, despite the spikes, the sub has settled lower than I had anticipated into the carpet. Hopefully the extra clearance will help. If not, I will contact Outlaw support.