jimmy225,
I agree with millercarbon, a pair of good quality subs are very capable of providing very good bass, that’s well integrated with your main speakers, if you’re only or mainly concerned with the bass quality at a single designated listening seat.
However, you’ll need to completely abandon the ineffective method of positioning one sub by each main speaker. The much longer and omnidirectional bass soundwaves launched by your subs behave completely differently in your room than the much shorter and highly directional midrange and treble soundwaves launched by your main speakers.
For best results, use the crawl method (google it) to sequentially and optimally position each of your subs in your room, which will typically be completely independent from the positions of your main speakers. In my experience, the likely best bass, at your listening seat, will be achieved with one sub positioned somewhere along your front wall and the other positioned along a completely different wall, which could be the back wall or one of your side walls depending on your listening seat position within your room.
I also suggest running your main speakers full range and setting the volume and crossover frequencies as low as possible on each sub as you can with the bass still sounding powerful, dynamic, detailed, smooth, fast and natural to you, as well as seamlessly integrated with your main speakers.
Best wishes,
Tim
