Gain level on a REL sub

Thanks for the responses. @soix I have not tried that crawl method but would be hard to do in my room. According to REL, the slope is rolloff a little to high. Rhythmik was one my option for a sub for some time.

@gkelly I have used high and low level connection and the gain is still the same level.

Hi @fastfreight I do have the phase corrected on the sub using a software from Rational Acoustics. The pros use this for phase and time alignment but for this is probably overkill. Honestly, if done properly you will hear it louder around the crossover point usually because of summation and that is what is great about this software. You can see the changes in real-time and not as a screenshot.

I appreciate all the help and recommendations. All of you have valid points and can't disagree. However, let me reiterate the situation I am having. With the Hsu sub I had had more of a "presences" feel to bass drum and bass guitar but still without the boomy and muddy sound I don't like. Perhaps maybe the Hsu sub was ported and has a lower response than the REL that I am use to. In the contrary, the Rel just disappears but in a good way. I feel it producing the full audio spectrum and not a sub/sat combo even though it is. 

I am actually using the high level connection and it wired properly. red to R, yellow to L and black to common ground on the amp chassis based on REL recommendation. As for the phase switch I have it 180. I have data to proof they are phase aligned. All you have to do is read phase traces on a graph interpret the slope angle. Again, I use Rational Acoustics for this since I have it available.

As of alot of you mention if one of the option was a defective sub. I really don't see or hear any defective issue with the sub. Maybe the gain staging in the Rel amp is not high enough but still is sufficient for my needs. 

Overall conclusion to this is that REL sub is sufficiently great as long as it produces clean, musical bass with detail and definition. 

@jji666 Yes, i am aware of them being different  sounding subs. They both are great subs but in different perspective means. As far as the far as the gain setting, it is not maxed out.  It happens to be at a little before 3/4. 

@fastfreight I have color-coded speaker cables. I would have to be color blind if that was the case.

@wsrrsw @helomech what exactly do you mean by it us the wiring? Are you referring to the quality kf the cable or how it is wired. I have followed the recommendations that REL suggested.