Integrated Question

Rooms have positive and negative nodes  where bass notes are increased or decreased in level. This is elementary acoustics! Your listening spot can be in one of those nodes. Use the Stereophile Test CD playing bass tones while you walk around the room. You may have to rearrange all four speakers and listening spot to achieve an acceptable result.

Looks like I am the only one here discussing room nodes for bass. Such ignorance! Sure, go buy another amp - add more watts! LOL! Go buy some wire for use as a tone control! LOL! 

The flattest bass response in a room is having the woofers placed at the boundaries of two surfaces, i.e. the walls and floor. Putting woofers away from surfaces yields the most uneven response. Roy Allison discovered this decades ago and used it to produce a line of speakers with exceptional bass response.

@jasonbourne71 

I am completely with you on how vital the room is in ANY setup. It is amazing the majority of rooms I’ve heard have very little attention paid to the acoustics of the room 

Don't spend a penny on new equipment or cables until you have verified your set up is not the problem. 

It could be as simple as the speakers, subs, or your listening seat are in a null. It could be that there are phase issues between the mains and subs creating a cancellation. 

Try turning the subs off and listening to just the mains. Does the problem persist or is it reduced? Try moving the mains both forward and listen, then back and then listen. 

Try playing the subs only, and see if the problem persists. Try moving the subs out to about halfway down the side walls. 

Try moving your listening seat forward or back in the room, both with and without the subs. How does the bass quantity and quality change? 

There are too many things that can be tried for free to diagnose what is going on. Randomly buying cables and components is more likely to result in a lot of money being spent and still not getting good results. Your components should have more than satisfactory bass quantity and quality when properly positioned and set up in the room.