Hey Jdtalv,
I would say that it is a horse apiece.
I also was debating between a Rythmik F15HP and an SVS SB4000. My feeling was/is the Rythmik servo technology is a better design, I ultimately ended up buying two SVS SB4000 due to my interaction with both companies. Though my interaction was not bad with Rythmik, it was not as professional as my interaction with SVS and since Rythmik is direct sales only I was a little concerned about how I would be treated if I ever happened to run into a problem. They both have at minimum 30 day trial periods so you could try them out in your system.
I also agree that any high quality sub will more than likely work in your system as long as they have a low pass filter (usually incorrectly referred to as a crossover) and phase alignment capabilities. (not just a polarity switch)
Since you say this system is primarily for music you will want a SEALED sub, not a ported or a sub with a passive radiator, and you will want to plug the port of your KEFs. If the KEFs start to roll off at 100Hz you will probably experience directionality from the sub so I also would recommend a minimum of two subs.
Lastly you should also check out http://www.soundoctor.com/ for some excellent integration techniques.
I would say that it is a horse apiece.
I also was debating between a Rythmik F15HP and an SVS SB4000. My feeling was/is the Rythmik servo technology is a better design, I ultimately ended up buying two SVS SB4000 due to my interaction with both companies. Though my interaction was not bad with Rythmik, it was not as professional as my interaction with SVS and since Rythmik is direct sales only I was a little concerned about how I would be treated if I ever happened to run into a problem. They both have at minimum 30 day trial periods so you could try them out in your system.
I also agree that any high quality sub will more than likely work in your system as long as they have a low pass filter (usually incorrectly referred to as a crossover) and phase alignment capabilities. (not just a polarity switch)
Since you say this system is primarily for music you will want a SEALED sub, not a ported or a sub with a passive radiator, and you will want to plug the port of your KEFs. If the KEFs start to roll off at 100Hz you will probably experience directionality from the sub so I also would recommend a minimum of two subs.
Lastly you should also check out http://www.soundoctor.com/ for some excellent integration techniques.