@jeffrey75
My room is known for swallowing low frequencies. The footprint is 14’x17’ but the ceiling reaches 17’ for the whole room and is open to the second floor and the rest of the house. (wide open floor plan).
I have the ULS-15s set up to the outside of each speaker (KEF 107 Reference). One is in the front right corner, the other is against the front wall, but has no wall to its side. As mentioned earlier, they are EQed using the SVS AS-EQ1.Since the KEFs dual band-pass loaded 10" drivers can be tuned using the Kube EQ, I have more flexibility than most in tuning the low end.
My setup is mainly for music. As far as subs (any brand) are concerned, I feel they’re a little harder to convincingly integrate for music than movie effects. Before adding the SVS EQ, I did have a hump around 25Hz on the right side of my room. The EQ-1 was able to flatten that hump and the response across the range.
Before adding the KEFs to my system, I was using a pair of Gemme Audio Tanto IIs which were a great speaker, but didn’t have quite enough weight, and I relied on the subs a little more for the lower frequencies. When I swapped to the KEFs I re calibrated the EQ-1, and found that the ULS-15s don’t need to work as hard.
As for the sound, I’m completely satisfied. You cannot tell the ULS-15s are even running since the integration with the KEFs is spot on. While the KEFs are ported (near the neck of the speaker) I am a fan of sealed designs, especially for subs. I feel the bass is tighter, faster and more to my liking for music than ported designs. But, the ported designs seemed to work just fine if you want the effect of dinosaurs smashing through your home theater.
Since the OP is looking for a home theater sub(s), I feel the ULS-15 would be more than suitable while saving money over the JL option. It’s an $1800 price difference, and I personally don’t believe that (for movies) you’d be able to justify that split in any noticeable difference in performance.
For the price point of the JL (apx $1900 per) I’m more likely to recommend the SVS SB16 for the same money. I owned a pair of their SB12+ when I was set up in a smaller room, and was very happy with their performance. I kind of regretted selling them. I believe they still have an in home trial period, and the SVS team stands behind their product.
I hope this helps.