SabrinaX Sub-Crossover

First time posting. I recently got a new pair of SabrinaX speakers and paired them with two Martin Logan 1100x subs. The system together sounds incredible. The SabrinaX is rated down to 31Hz. Where should I cross-over the subs? I did it at 35Hz with a steep roll-off (4th order) but wondering if people with more knowledge have any recommendations? 



The subs crossover should be set at least 10 hz over the lowest frequency rating of the speakers. Mine are set at 13.5 over.

One thing I should have mentioned, is that in-room performance of speakers has almost nothing to do with the specified or quasi-anechoic (Stereophile style) measurements.

Room gain is real, as are room modes which can move the bass output singificantly up or down.  Setting a sub or crossover by published specs is really tough compared to doing it by measurement.

This is all very helpful information. I will definitely take measurements in the room but leaning toward not using subs at all now. I’ve felt that the bass has decreased the quality of the sound which is likely a reflection of both integration and how good the SabrinaX are. 

I found dual sub use with a two-channel set up to be more trial and see what works as opposed to a specific formula.  So much depends on the equipment and room set up.  

I'm also using a pair of Martin-Logan subs to augment my DynAudio Contours (which already have strong bass response).  I wanted full effect on the very low end but I didn't want them to over play low end bass lines.  After several attempts and some advice from Get Better Sound;  I have them set up just in front of each speaker, laying on their side (they are bottom firing) so that they fire at the wall behind the speakers (set up for 13' x 11' room).  The cross-over is at about 38-40Htz, phase 0 and volume is only at 1/4.

Basically, 80% of the time I don't even know they are there. They don't color the music be it Rock, Jazz or Classical until a bass drum or deep bass line is emphasized and then the bass sound is tangible.  You can feel it without distortion; like a live performance.  On something classical like the 1812 Overture; the cannons are a down right scary rumble.  For an acoustic trio the bass line sounds like its in the room. 

But that was the goal only wanted to capture the ultra low that the speakers couldn't reproduce. Also noted I set my system to direct without EQ or gain on bass or treble.

Additional note, I’m using AudioQuest sub cables with a splitter so that I occupy both L and R input ports on each sub.  See the last picture (empty sound stage) in my profile for visual on set up.