Sabrina X Anyone Add Subwoofer(s)

If you are considering spending $5k on a sub that suggests that you could have afforded the Yvette that has a 10" woofer that goes down to 20hz. With the right amplifier probably solid state power, that drives a difficult load 86db and 4ohms, I would hope if you can't get enough bass out of them then there is something fundamentally wrong.

No.  Subs are much more than just getting “enough bass,” and your statement indicates you’ve never heard a good system with properly integrated subs.  Too bad because there’s much more to it than just more bass.  I’d take the Sabrina X and two good subs over the Yvette any day.  Once you hear what subs can add to a system you won’t go back to listening without them. 

Yeah the Sabrina with two of Wilson’s new subs would be amazing. They have proper built in highpass crossovers. I would put it up against any of their speakers. Just in concept anyway. 
 

In reality the only difference between the smaller abs larger speakers is low bass output. Sure there are other difference but… not really. 

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.

Lots of great information.  I now believe that two subs are best.  I also agree that I should wait to see if I need to go that far.  I'm really not looking for more base as much as more authority and clarity.  I really don't want a high pass filter.  I bought an integrated amp to simplify things and I assume that Wilson put a lot of work into the speaker's internal crossover.  I don't want to interfere with all of that, so I'm guessing that a 35-40hz crossover and a steep slope.

OP,

+1 wait +1 two subs if you decide to go with subs.