Okay. Major updates.
I stuck an HRT Music Streamer II in my signal path. My sub amp is no longer input voltage starved and it really pounds now. Before this, I was not able to bottom out the 12" Dayton Reference with a 20 Hz Filter in place. Now I can with 75 % gain... big difference. Oh, and besides the voltage, the HRT seems to have improved my sound quality significantly. I got it for a steal on Ebay. Under $100 like new.
Speaking of prepping, I've been working on the sub. It was hard to take it apart, but progress must be made.
I skinned the top and back with 1/8" HDF (hardboard). I was able to flush the top with the front baffle, so it was pretty seemless.
The purpose of this was to cover up seams and screw holes more completely, and to add just a touch more mass to the top and back panels.
I did put a heavy layer of bondo on the inside of the woofer cutout. This is because there were several voids, one of which actually leaked out the side!
Top top edges are chamfered, the front sides are 3/4" roundover, and all other seams will be 3/8" roundover. I have had some problems with the cheap plywood. The thin outer ply splinters easily and I've had some big voids right on the edge. I've used quite a bit of bondo and I have probably 2 more "coats" before I am fully satisfied. I wish there was a "thinning agent" for Bondo. Maybe I will have to get the "glaze".
Just weighed it: 62.4 lbs completely empty.