Sabrina X Anyone Add Subwoofer(s)

A subwoofer can certainly improve clarity by using them to smooth frequency response. I would highly suggest room measurements to better define your issue before going further. Measurements are an efficient and accurate way to improve listening experience when it comes to bass. The implementation is going to be more important than the model, but there are obviously different approaches between subwoofer brands. REL and JL are very different as reflected in their setup tips and feature sets. Obviously the use of multiple subs gives the opportunity for both increased output frequency smoothing by way phase adjustment. I will say though, that the DARO feature on the Fathom line is powerful and worth consideration. I have a pair of them, and DARO kind of takes the challenge out of finding the perfect spot. With my RELs, there was more placement adjustment between them and my main speakers. I owned the S510s which proved not an ideal output match with my speakers, despite the REL site recommending the T/9. This isn’t against the S510s, I just find the REL suggestions less than perfect.

The reason to high pass main speakers is to keep them from messing up the bass if they are messing up the bass. I begrudgingly bought a crossover one only to solve that issue. The phase control on JL audio subs is set at 80Hz, which is their preferred low pass crossover setting. Smart to be aided by a dealer although you may want to clarify what their process is in helping you set them up. I highly recommend measurement software like REW. The Sabrinas are charming speakers, best of luck.