Subwoofer for Kef LS50 Wireless II?

+1 fiesta75

audiocanada, Your SVS SB1000 subwoofer is capable of a some sophisticated application based equalization and Q adjustments which can be varied to taste and preset to memory. 
Along with audiorusty's crawl test suggestion the result should be spectacular regardless of source material.
Are the adjustments and positioning overwhelming?

I've used many subwoofers for public address and in home including REL.
What is REL magic?

audiocanada, clearly your not overwhelmed by the SVS application. I hope your within the SVS audition period and able to return the unit.
Unfortunately, subwoofer digital processing is not equally designed.

Aside from my Velodyne Plus' my only other first hand experience with your short list was with JL Audio's v1 A.R.O. which auto equalized the loudest peak with no manual EQ adjustment. Their D.A.R.O. v2 is a multi band auto equalizer. Their CR-1 has a great deal more manual control.

There are third party products such as DIRAC which seem to have the flexibility your room may need. I hope you made note of your rooms loud bass modes and its nulls as you usually only need to do this once.

The AudioKinesis Swarm subwoofer system is another alternative that many have found very satisfactory.
Your in the mob now, don't give up. 

    

audiocanada
update,I now have the KC62, long story short, perfect marriage
integration took seconds with the app, set it and forget it, no looking back
trying to resist the urge to purchase a second unit
it does not have the output capability of the SVS
app control on both units is superb, I'll never do subs again without app control, no going back, I read a blurb somewhere that both JL Audio and Velodyne will be releasing new app controlled products

Congratulations. Glad you got past the dissolution of your 05-14-2021 post.
By now you should have had the experience that not all media contains extra low frequency content. But when it does you've got it covered. 

I'd be very interested in that blurb about JL Audio and Velodyne releasing new control application. 

No moss grows under your system. I'm sure the differences you're experiencing between the your original SB1000 and this current SB3000 would be of interest to many.