Where are the subs?

Using the long port, KEF states it can get to 30Hz in-room at -6dB, so not much of a surprise.

However, audio <40Hz that needs real power is best handled by a subwoofer.

Despite the specs. I highly doubt your 10” sealed subwoofer can get to 25Hz anechoically.

Play the opening scene of the movie Edge of Tomorrow, that is an amazing test on the bass extension of your setup, it goes down to 10Hz (start with the volume low to prevent potential damage).

Hello dbphd,

     I'm glad you're enjoying your system so much in a new room.  However, I believe your initial experiences in your new room are more a fortunate combination of factors than something you can rely on experiencing on a consistent basis with a larger sample size of source material.
      Your  Kef Ref 1 monitors, I'm assuming on speaker stands, are excellent speakers with exceptionally good bass extension for a monitor type speaker of about 40 Hz.   As you know, The Bach Toccatta and Fugue BMV565 has deep organ notes that likely require the full bass extension of the Kef's bass drivers at times.
     I would highly recommend utilizing your Velodyne HSG-10 subs and your xover in your system.  Not only because you'll be gaining the capacity of high quality bass reproduction of most of the bottom octave in any music (16-32 Hz) but also because you'll be relieving the Kefs of the burden of trying to reproduce bass frequencies at their woofers' physical limits of about 40 Hz.  
     There's also the added benefit of relieving your amp(s) from needing to supply the significant power the Kefs would demand when attempting to reproduce bass frequencies near their limits.  You'll notice the Kefs have an improved sound quality performance from the mid-bass through the midrange and treble with a greater sense of effortlessness when you add your subs and xover back into your system.
     You may also notice overall system performance improvements by raising the low-pass cutoff frequency a bit.  
   
     If you'd like state of the art bass response in your new room, utilizing 4 subs in a distributed bass array configuration would provide it.

Tim
  

The 14' X 19' room used for HT as well as music has a 100" projection screen, and two HGS-15s with SMS-1 bass manger that can make you feel pressure on your chest.  Unfortunately, both need repair, so the only functional subs in the room are two HGS-10s that are not connected.  I'll reconnect the HGS-10s, but really need to haul the HGS-15s to LA for repair.

It's great to get a pleasant and unexpected surprise once in awhile.The room is so important!I'd be interested to know your impressions with and without the subs. 

wait a few weeks before you try to put the subs back in...the room and set up are certainly crucial, but there is only so much deep bass those speakers can put out...