Considering Vandersteen Treo

My only thought is that a two way is just not covering all the bases, and a three way, or in the case of the Treo four way, might solve the problem. 

Yeah it might, and I’m a big Vandy fan so not surprised at all that you liked the Treos so much.  If it was me and especially with your sized room I’d buy a couple SVS SB1000 Pro subs (currently $1149 for a pair) and see what happens.  My guess is not only will you get the additional fullness you’re looking for but your soundstage will expand significantly and you’ll get honest bass down to 20Hz (-3dB) that you can tailor to your room (much tougher to do with more full range towers) with their included software.  If they don’t change your world you can return them after 45 days completely risk free, which is obviously not the case if you experiment with used floorstanders.  That’s definitely what I’d explore first all things considered if you can physically manage two small subs in your room.  FWIW. 

https://www.svsound.com/products/sb-1000-pro-subwoofer

@zlone I have two reasons:

I have heard Vandersteens at dealers and in homes. I was never impressed. It was lean, dull, mediocre sound. There were details and dynamics but it felt - for a lack of a better term - just for measurements’ sake.

If you liked them, you should absolutely ignore me.

I also have the Ones and I like them a lot. They sound way better than anything else I had heard from Vandersteen. The setup is also different, it’s a small space. They are not my primary speakers mainly because the tweeters are way below my ears.

I had a friend over at my house who is about 10 times more knowledgeable than I am. I asked about this paradox - Ones in a small space - good, new models in bigger spaces - not so good. His take is that the Ones were a simple and lucky copy from another brand, way back when. They work very well. However the next generations didn’t get anything right. They have more drivers, more expensive components, but there is no design and synergy that yields a better sound. 

It sounded credible to me but of course I have no facts to back it up. Obviously my friend does not think highly of Vandersteen. It matches my experience that I would never want anything other than the Ones I have.

I am a monitors+sub guy, I don’t need big sound, big space, I want sound that moves me, sound I can connect with. I am also low budget, the Qln 3s are very high end speakers, and I don’t know anything that’s better (from personal experience). With your budget you can try a lot of speakers - hence my list, based on numbers, reviews, sessions at friends’ houses, etc. 

I should add: I am not here to argue about how good Vandersteens are, everyone is entitled to their opinion.

Your room is small. TAD ME1. I heard them at a show and they were special. But more importantly, an audiophile friend changed up his Vandys for these, and he does not compromise!

@mapman The Totem's look interesting, I will read up on them.

@2psyop This is good advice. I am obviously on the fence.

@soix I may try a sub again, but the whole goal going from standmounts to floorstanders, was to get it all in one package. It is not important to me to have bass down to 20 Hz, and the QLN's already hit the high 20's, though probably not with the force of a sub.

@parkergetdean Thank you for the detailed response. There are few 'facts' beyond measurements when it comes to speaker selection, just too many variables, the greatest being the listener. I appreciate the opinion.

@noromance Yeah, TAD. I have been to AXPONA the last two years, and I could kick myself for missing the TAD room both times. I really want to hear what all the fuss is about. People universally love these speakers. And FWIW, I heard the Vandersteen Quatro's at AXPONA and all I could hear was the speakers themselves, which tells me they are probably very position dependent as I was a couple rows back from the hotseat.

Thanks for all the comments. I will keep my options open for a bit.

It is not important to me to have bass down to 20 Hz, and the QLN's already hit the high 20's, though probably not with the force of a sub.

The point of going down to 20Hz isn’t all about bass — there’s critical information down there that contains spatial cues that greatly enhance soundstage and imaging as well, which I know are important to you and why I thought subs would be of particular benefit among potential other things (added heft/fullness).  If you’ve ever heard a good system with properly integrated subs it’s why the whole soundstage collapses and imaging suffers when the subs are turned off.  The difference is striking.