Yeah, it's been in place for a few months now. Hasn't changed much, although as I got more used to it the sound levels seemed to taper off.
I've been playing with all the different settings the whole time. Any change I make to get more output (increase gain, increase bass EQ on amp, up volume on HU, etc.) just gets me distortion. I've done pretty much everything except bust out a voltmeter and get crackin with some measurements. Which is why I made this thread. I tried searching but all I could really find was some wiring diagrams and some methods for measuring amplifier output.
I guess one other possibility is that the amp may have just been bad from the start. First amp I've ever had go bad and I was way kinder to this amp than the ones I had in the 90s.
As for the box, its in a sealed box mostly because that's what I had some experience with. Sure ported would get me more output, but I just don't see that being the difference between my expectations based upon past equipment and what I'm getting from this setup. On this topic, another comparison to throw out there. My friend has 1 10' sub running on a 300W amp (forget the brands), I'm pretty sure his is noticeably louder than my 12" running on the supposed 900W. At best they were of equal volume.