Where are the subs?

I agree with dbphd.  I am going to be adding a pair of F12 Rythmik subwoofers to my system to exactly the same thing.  I tried to like the REL subs, but could not hear what a lot of audiophiles claim to be incredible.  Since a REL T/9i is rated at 28 Hz at -6 db, I have been told it is lucky to play down to 35 Hz.  That is woofer territory.  However, perhaps that is why they blend in so much.  However, if you can't hear that much of a difference why bother.  I don't want to hear a boomy bass sound take over my system.  I just want to hear all of the frequencies available on a recording.  There is a lot of music recorded that gets down below 24 Hz and I want to hear it.  I will try to set up my subs at low volume so they will not stand out and blend with my towers.  I talked to Brian at Rythmik and he explained why he came up with his Direct Servo technology.  I also talked to a highly respected speaker manufacture and he told me the Rythmik subs are the most musical subs he has ever heard.  This is why he builds custom subs using Rythmik drivers and amplifiers.  Just hope I will be making the right decision.

The organ is introduced in the Saint-Seans 3rd symphony by a pedal note that is more felt than heard, and the big KEF Ref 107/2s reproduced it nicely.  That note is entirely missing with the KEF Ref 1s, and likely to remain so even with the HGS-10s.  I suspect it will take the HGS-15s to recover it.  But I rarely listen to that symphony, more often Bach, Corelli, Mozart, Bill Evans, or Miles Davis, all of which are covered well by the Ref 1s.  I am committed to implementing the four subs, but I do wonder if it's worth the bother to hear such rare notes.

I had used a fully balanced passive 80 Hz 24 dB high-pass Marchand filter between the Ayre preamp and amp with the subs low-passed at 80 Hz 24 dB, but I'm not using that either.  The HT setup includes four LS50 surrounds that are currently inactive.  I do like the simplicity of just a pair of speakers.

I’m not shocked either.   Recently put in full blown home theater , room is treated and fronts are full range.    Room is critica.    Same speakers in a different room with same electronics they sound bass shy.   However I. The basement theater they hit 20hz down 3db no problem.    Dunlavy sc 5s

Recently added a REL S/5 Sho.  Connected it via the high output option.  It did add some additional bottom but more than that added a spaciousness to all my music that wasn't there before.

I had similar experience when putting new (old B&W) bookshelf speakers in my office. Surprising amount of bass compared to older B&O. I added my Velodyne Servo 1200 back in old settings, new location. Way too much bass. After I got it proper, the sub is adding just a little bit, you are unaware it's on until you turn it off. You probably can get that slight but unobtrusive extension also.

Same thing with rear surround, most people have them too loud. Most of the time you should not be aware of them, until, turn therm off, the image crashes to the front.