Subwoofer

Dear @jpwarren58  : The main issue could be not if you need one or two subwoofers.

The main issue is that your really good Ryan speakers are a two way design crossing at 2khz and even that maybe you don't know that same woofer/mid-range driver goes down at least to 35hz and : what does that means?.

It means that the speaker has a very high IMD that comes from its bass range notes/harmonics that puts alot of " trash/dust " to that part of mid-range sound. That woofer at the same time that's reproducing 40hz-50hz is reproducing frequencies not only at 2khz but even a little higher, so the woofer excursions goes and degrades the mid-range frequency with that developed high IMD and this is the main issue why you need not one but two subwoofers connected in a way that the Ryan handle all the frequencies over 90hz-100hz and the subs below that frequency crossover. 

In that way the low bass range will be reproduced by drivers designed to handled that critical low bass range ( in an audio home system MUSIC belongs to the bass range, as better this range as better what you are listening. ) and along dedicated amplifiers designed for that bass range. So now your mid-range will shines as never before and the HF too as the bass improved.

Btw, Dirac Live digital process can help you and any one else not only to integrates subs in any system but will improve everything in any home room/system.

Regards and ENJOY THE MUSIC NOT DISTORTIONS,

R.

I'd like to help but I'm confused.  OP is asking for a help pairing a sub to a two channel listening system but lists both KEF R3 AND KEF LS50 as the speakers.  I'm confused.   

I have an SVS Cylindrical Sub that has a small foot print, but vertically it is quite tall for my HT and I have two Hsu subs for my main stereo system. Two smaller subs will give better in room performance than one larger one IMO, but no harm in trying a single first. If you contact Dr. Hsu at Hsu Research and give him your room dimensions (including doorways) he will work with you for best results.

Dual rel subs are a good option for filling in the mid low bass like bass guitars very well. But for the super slam of HT and organ music that you can feel, Earthquake Sound has something called the tactile transducer. When mounted under chair or couch, your bass will no longer be an issue. 5-40hz.