Full-range recommendations

Warm and open...sounds like Sonus Faber to me...especially slightly older models...going from your current monitor to another is a lateral move...have to move air for bass...takes a larger speaker...personally...with speakers as good as Ref A...I would add sub

I also agree with Phasecorrect: although I suggested the LSA 2.1 Statements, your situation is practically begging for a sub or two. Your current speakers are excellent from around 50 Hz up and your room is not very large. A viable solution is to add a sub or two to fill out that bottom octave. The advantages of powered subs are that some of them have high pass filters that limit the LF signal going to your little monitors, thereby making them clearer and more dynamic in their natural range, you can experiment with the subs' crossover points, phase relationships, and bass output to match your room, and you can locate the subs in-room where you get the best bass response while you place your monitors where you get the best soundstage and imaging.

If you get the first Stereophile test & demonstration CD, it has test tones from 1Khz down to 20 Hz and makes it easier to get flat bass response from the monitors' output down to the lowest capabilities of the sub(s). I find it easier to use this tool to integrate subs with sats than it is to move big heavy full-rangers on an inch at a time one way and another to try to get best imaging, fewest room resonances, *and* best bass linearity and extension.

Right now Audio Advisor has the MartinLogan Depth 3-driver sub on sale for$1349.10 through Sunday. It has a high pass crossover settable to 40 or 70 Hz and low pass to the sub ranging from 30 Hz to 80 Hz. Its bass extends down into the 20s, yet it has its own volume control so you can get your best bass extension without overloading your foom. It features three 8-inch aluminum cone drivers for fast transient response to blend with your Reference
3As while offering the radiating area of a 15-inch driver for bass slam and depth.

If it doesn't work out for you, AA has a 30-day trial-and-return period and all it costs you is return shipping.

Disclaimer: I have no relationship with Audio Advisor except as a satisfied customer. I have no relationship with MartinLogan subwoofers except as an impressed listener.

ATC-SCM40's? They are very revealing speakers though. Silk dome tweeter and a magnificent domed midrange. They reach down lower than their specifications would lead you to believe.

As far as 'warm' speakers, I'm surprised no one has suggested a B&W speaker...

Spendor SP100R2. I've seen them lightly used in your price range.

There is a pair of Spendor SP1/2R2 for $4200 on
agon.
I meant SP100 not the R2 version in my
previous post. However I did see 2R2s for
a great price once.