I received my D15SE yesterday.
It is a great looking sub and was packaged very well.
I was getting some buzzing due to a ground loop, but a cheater plug took care of that - it is dead quiet now.
I hooked it up, ran Audyssey (sureshpc - Audyssey place my sub closer, by 6 ft, as well) and listened to some music and watched the latest transformer movie (only recent action movie I have not seen). The sound is very different than what I am used to. My last sub - a 1997 Velodyne VA-1012 was very in-your-face. I knew exactly were it was and I didn't use it for music because it sounds mushy to me. I crossed my fronts (Polk Lsi15s and a CSi40) at 70 Hz even though they can go down lower and listened to music. At first, it was strange because I didn't "hear" the subwoofer, but I know the lower frequencies were there.
I had the same feeling watching the movie. At times I felt like I wasn't getting the same punch, but then the pictures would start to rattle, which didn't happen before. I think this is all good, and is a part of experiencing clean bass.
I have a setup question, however. I understand that when watching a movie than the subwoofer can get information from two sources - the LFE channel and the frequencies stripped off the other speakers - anything below 70 Hz in my case. So what is the frequency range of the LFE channel and where should the LFE LPF be set?
Edit: Any suggestions for a good starting point for the cross-overs for the front speakers (my matching LsiC speaker arrives today)?
Polk LSiM703, LSiM704C, LSiM 702, LSi 7
Rythmik D15SE sub