Subwoofer advice sought

why stop with DBA?  Might as well just go ahead with full-on 3D immersive surround sound and go for the full monty of sound envelopment, right?  Afterall, if you aren't setting a reference at producing a live acoustic music sound stage then just immerse yourself for the experience.  We all like music presented in various way and there's no wrong answer....but being immersed in the music in an unnatural way isn't for me.  All venues have their unique acoustics and associated challenges...I don't often see 4-6 double bass players scattered throughout the venue to immerse you in their bass.

I tend to agree with @erik_squires on this one (but I wouldn't call it a cult - we all have a preference for how we enjoy experiencing sound and music).  Are we trying to envelope ourselves within a soundstage instead of having it presented front of us?  I actually thought the biggest merits of a DBA approach was not necessarily to envelope yourself in the sound (like you may want in a movie) but rather to combat problematic room nodes....so it's really a form of acoustic treatment and not creating a fake soundstage that envelopes you in it. 

Your Totems already reach down to 28HZ
What you need is impressive depth below that.

I researched subwoofers for over a year before buying.
What I learned was one big powerful cone is better than multiple small cones or passive radiators.
If I were buying now this one goes to 17hz or so they say.
Even if only practically 20hz... MUCH more oomph than the two referenced above.
https://www.svsound.com/products/pb-2000
Generally speaking you need a 12" cone to get to 20hz.
Listen to the attached video !

BTW I ended up going over the top with this;
https://hometheaterreview.com/definitive-technology-trinity-subwoofer-reviewed/
One of the best subwoofers ever.
Earth shaking in movies (literally) yet clean and pure for music.

Its just fun to watch peoples jaws drop ;)

Just adding in.  DBA setups do have the potential to give extraordinary bass.  If you have the money and ability to implement 4+ subwoofers in a sealed room with proper inverting cables or circuitry for the rear subwoofers, then go for it!  If you just want to beef up the bass/sub-bass on your Totems, then getting a nice single subwoofer is like a better choice.

I have heard Rel subwoofers.  They are nice and clean and have very good tonal definition down in the bass area.  Extremely clean.  But they are not powerful and meaty sounding subs.  If you want more of a meaty and gritty audiophile sub, I would look first at Rythmik ported subs.  There are others, such as Hsu and SVS.  SVS has a distinct tone that is popular with consumers of Best Buy, but it's kind of a one-note-wonder and doesn't have good resolution (in my opinion). 

The "subwoofer output" on your integrated is likely just a full range output.  I don't see any mention of a crossover inside and there are only 2 tubes.  The Vandersteen is an option if you want a try crossed over subs that blocks all bass from your main speakers.  The Rythmik would be if you were fine driving your Totems "full range" and just wanted a sub to fill in the missing sub-bass area.

I don't often see 4-6 double bass players scattered throughout the venue to immerse you in their bass.

If you've ever been to a rock concert or especially an EDM show, the bass travels throughout the venue and you feel it as much as hear it.  That's one of the great things about having multiple subs is that it feels like live music.  I don't recall ever hearing the bass only coming from the direction of the stage at a live concert.  Of course it's been a while since I've been to a show, perhaps my memory is playing tricks on me.