Can anyone hear the difference when you add REL subwoofers when playing two channel

I have 2 rel. this is how you set up high level input:
make sure the yellow and the red are twisted together and going into the positive left on your amp and the black into negative left, and do the same on the right outputs. Put the crossover about sixteen clicks and the low level at about 10 clicks from zero. Play a track w repeating bass line. Lorde “tennis court” is a good one.Tune one sub at a time with the other sub off. First flip the phase button and whichever way sounds louder is probably the in phase for your setup. Work the crossover back toward zero until you like what you here. Work the bass level back to zero until the bass level matches the speakers but just kinda extends the bass response. Do the same on the other sub.  You’ll have bass that is on stereo and match’s and extends your speakers. Look for better soundstage and clearly better bass and midrange. Listen to sympathy for the devil, listen to the bass guitar, you can hear the guitar 🎸 not just the beat but the actual instrument, you can almost picture the strings being plucked. You can mentally picture where in the stage the bass player ( Bill Wyman?) is standing. Now your all set.

You can also run LFE input on the rel in conjunction w high level. If you have a surround processor w lfe out, this will go into the rel and should only come on with movies that have an lfe track.

MAKE SURE that your not running high level out into the REL and LFE out into the REL HIGH LEVEL INPUT at the same time. The sub out or lfe out on your amp needs to be input on the rel lfe input, not high level or you’d be defeating the purpose of true stereo bass extension. 

I hope this helps 
-ak

@larry5729  I'm not going to bother going to the REL site to check but I would be highly surprised (to put it mildly) if the T9/i puts out 300 "class A" watts.  

See my post which is directly related:
https://forum.audiogon.com/discussions/kal-on-sub-integration-and-antimode

Audioman58:
Doesn't the SVS turn the towers in to boom boxes and throbbing bass?  Did you have the same problem I am having hearing difference when you add and subtract a REL subwoofers when 2 channel listening?  The dealer told me I am listening for the wrong thing, an added bass sound.

When I listened to the S3, I got on my knees and put my ear next to the speaker and it was not pulsing out the beat.  All it was doing was putting a steady humming sound.  Hard to describe.

I believe it will only Throb with bass if the REL's low pass filter is "listening" for such frequencies. If the REL is set at 30Hz, but the Throb frequency is happenging at 40Hz, then the REL won't play it. That hum may well be the reverb/transient information and could be normal. Play music that for sure thumps at 28Hz then check again. Probably wouldn't want to get your ear right up to it.