Input on speaker sizing for a lively room.

My listening area is a 34x22x8 open floor area of our home. It is comprised of both a great room and the kitchen/dining area. Flooring is hardwood with typical rugs where appropriate as well as having some large windows. My listening is two channel audio only and often while casually doing daily routines with the family.

My system has evolved to a point where I feel a plateau has been reached. Listed as fallow:

Herron M1A mono amps
Herron VTSP-1A-166 pre
Arcam CD23T CDP
Morrows Mid level cabling
Dunlavy Cantata

My current speakers are Dunlavy Cantata's located on the interior long wall. These speakers perform quite nicely at mid level volume. Where I would like improvement is both at low volume listening and some shear gusto above mid volume with a smooth top end. I realize the Cantata's are being unfairly critiqued here as they certainly are out of their design element.

Some personal speaker criteria. While my listening area is large, I would prefer to stay with a slightly undersize full range floor stander speaker for WAF. We have a quitar and piano player in the family so those traits are strongly admired. My budget would be 15K. A few speakers I have on a short for a demo are as fallows:

Silverline Boleros
Vandersteen Quatro
Verity Sarastro

General comments: Everything I read about Silverline sounds like utopia. Having talked with Alan Yun several times, his passion is inspiring. I have listened to the Vandy's briefly in a studio as they are local. It was that event that made me stop and decide to take my time with this decision. I could listen more if the sound was acceptable to more attuned ears in the household...

Feel free to offer up any input. Like many, I am at an age where this opportunity won't likely be repeated and would like explore possibilities I likely would never have known about. Thank you

For low volume performance, you need a symmetrical room. No amount of money spent on speaker can fix the room.
Your Cantatas are already better than the vast majority of speakers. Match it up with one (maybe two) sealed quality subs and you might never need to look back. Of course, there are the Dunlavy Vs and VIs out there which are still competitive with the best speakers around. Also, I might mention that the Schumann Resonance tweaks from companies like Kemp and Acoustic Revive work beautifully with Dunlavy products and may get you where you want to be without having to shell out anything close to 15K.
If you can hear the Acoustic Zen Crescendo and Vienna Acoustics Liszt, those two would come to mind. I have Herron electronics and am now using the Liszt in my room. It's a wonderful speaker and does a lot of things right. It's a sleeper in their line. I haven't heard the Silverline or Verity. I have heard the Vandersteen Quatro and 5A carbons. A lot of folks love the sound of the Vandersteens but I don't. To me the midrange seems thick and congested and the bass isn't well balanced. Again that's just my opinion and your ears may tell a different story.
In a room that size, especially given that you have an open floorplan, imo looking through a somewhat unorthodox lens is called for.

Presumably most of your listening will be done fairly far from the speakers. As a result the ratio of direct to reverberant sound will be low, meaning that the reverberant sound will dominate your perceived tonal balance. So the relative importance of the off-axis energy will be much greater in your situation.

Also, it will not be easy to generate satisfying bass energy in a 34 x 22 foot room, especially when it's open into other rooms.

Most home audio speaker systems give much higher priority to the first-arrival sound than to the reverberant sound, and most of them are designed with the expectation of some reinforcement in the low end from the room.

Finally, the dynamic requirements to reach "realistic" sound pressure levels in such a room are greater than most home audio speaker systems are comfortable with.

Not long ago I assembled a system for a room four times the internal volume of yours, which was similarly open into other rooms. We paid a lot of attention to keeping the off-axis response smooth and well-controlled, in this case using a very gentle constant-directivity waveguide driven by a high quality compression driver, crossed over to two high quality 12" prosound midwoofers at the frequency where the woofers' radiation pattern matched that of the waveguide. Custom subwoofers delivered the bottom couple of octaves. If this sounds like a high-end PA or studio monitor type approach, it is; imo that's what it takes to really do the job well in such a large room.

I understand that you are looking for a smallish floorstander for the sake of WAF, so the specific approach I'm advocating may be impractical. So as you audition speakers, you might try this: Turn the volume level up a bit higher than normal and walk out of the room. Listen through the open doorway, but without a clear line-of-sight to the speakers. From out here, all you can hear is the reverberant field. Does it sound like there's live music happening back in the room? If so, put that speaker on your shortlist.

In my experience two welcome side-effects of getting the reverberant field right (assuming one gets other things right as well) are good tonal balance throughout the room (and even into adjacent rooms), and fatigue-free listening for hours on end. Note that supporting a natural-sounding reverberant field is what a good recital hall is all about. If a live piano sounds good in your room, a speaker that gets the reverberant field right will as well.

Imo, ime, ymmv, etc.

Sounds like a job for the top Gallo Reference to me .
Sounds like a job for the top Gallo Reference to me .
A large OHM as well.
Joseph Audio Perspective would be another one to look at. Best of luck.
Some very good information to digest and then reevaluate my goals. Thank you to all who offered up there time for my benefit.

Goose...I would have to agree with your Vandy assessment. I was ready to purchase but was just not drawn in like I had hoped.

Some other room specifics. While the 34' x 22' room is basically open, there is a 10' long pony wall with base cabinets (kitchen side) dividing the total room in half. The ceiling also is not flat and has three separate 8" lowered perimeter soffits outlining the sitting area, dinning area, and sink island. The speakers are located in a 17'x 22' area segmented by the pony wall. The build design and interior settings are what had me aiming for an undersized speaker according to total room volume. I have no experience in what role the design elements actually add or subtract if any.
From your initial post:

"I am at an age where this opportunity won't likely be repeated and would like explore possibilities I likely would never have known about."

And from your second post:

"I have no experience in what role the design elements actually add or subtract if any."

Since it sounds like this quest is a major undertaking with high stakes, it might be worth a few hours of your time to dig into the topic of loudspeaker design. I'd like to suggest two first-class sources of information on the topic. The first is, "Premium Home Theater: Design and Construction", by Earl Geddes. This book is available as a free download. Don't be put off by the title - this is one of the best books on loudspeakers out there. Earl is one of the most intelligent people I have ever met (if not the most intelligent), and we are fortunate that loudspeakers are his passion. Just read the chapters that apply and ignore the ones on video systems and room construction, and you'll be the smartest guy in any room that doesn't contain Earl Geddes:

My other recommendation is Floyd Toole's book, "Sound Reproduction: The Acoustics and Psychoacoustics of Loudspeakers and Rooms". This is arguably THE definitive work on the topic.

One of the other (or both) of these will be time well spent towards making this a particularly well-educated decision on your part.

Feel free to ask me questions, I'm not as smart as either of these guys but have been digging into their work for a good while now.

I would 2nd the recommendation to give the Gallos and Ohms a try. Having owned both brands (the Ohm Walsh 2s back in the early 80s and currently have the Gallo Ref. 3.1s) I can tell you that both of these brands do a very good job of producing an exceptionally large "sweet spot".

I truly love the sound of my current Gallos and will probably keep them for the rest of my life. Another bonus is their small stature (big WAF points here!) and their very rugged construction. I bought mine right here on A'gon and you can find them in very good condition for around $1500/pr.

I've heard that Gallo is working on a Ref. 4 version, but no solid info. as to form factor, price, or release date...

Over the last couple months, I have spent a fair amount of time scouring the local audio shops and their inventories. While I live very near a major city that experience was an eye opener and not a good one. So in looking for a more diversified product information, I started calling manufacturers, many of whom used to have a presence in this market. Not having the funds and time to literally fly around and demo product, I am relegated to doing what research I can on my own. This forum is a tremendous resource in that endeavor and as time allows I use it.

My goal is to narrow down a short list of speaker candidates then do what it takes to listen to them. I am becoming more focused on the speakers being quality built highly efficient full range floor standers. They should also be able to be driven well with my current Herron amps.

Again, Thanks for everyone's input.
Ohm, Gallo, and MBL (budget permitting) were the first three names that came to my mind. All are nearly omnidirectional thru much of their passband. An array of subwoofers might make sense, too, although that might be a decor issue.
I also have a large space. One thing that I learned (the hard way) is the importance of in-home auditioning. Very few B&M stores have large listening rooms. Speakers that sounded great in the store "died" when I got them home. Your budget is sufficient to negotiate an in-home trial, however short. Also, there are manufacturers that sell direct and allow in-home trial periods of up to two months - such as Zu and Tekton.