Move your sub

Proper sub integration starts with the room position that gives the smoothest response as measured at the listening position.  For my sub it happened to be just outside one of room corners in front of me.  
From there you can adjust continuous phase (a required feature), polarity (a required feature), crossover and level to phase and time align with your main speakers.  The result is seamless, non-directional perfect subwoofer integration and optimized power response.  

@contuzzi

true, the phase adjustment does add delay but it has always worked for me.  my typical method is to reverse polarity on the sub and take an RTA measurement using uncorrelated pink noise.  It is easy to spot the main speaker's roll-off frequency.  Adjust the crossover on the sub to match, measure again.  There will probably be peaks or valleys near the crossover frequency.  Adjust the phase angle to flatten the response and then adjust the level by ear. 
Another important consideration is to avoid pre-amp connection to the sub and always use speaker level connections.  Much better for the sub to see the amplified signal that is identical to the signal the main speakers see. 
I use this method and have a completely smooth response curve with one sub from 20Hz through the midbass region.  It is non directional and bass comes directly from center stage- no peaks in the sound and as you said absolutely no room correction or EQ.  It sounds perfect.