Single driver full range speakers

@ronboco I get where you mean and that’s what I thought at first as well. On paper the magnepan 3.7i’s go down to 35 hz but that is a joke IMHO. I’ve also owned many speakers rated to go down into the high 20’s. They all needed subwoofers. 

I was initially using a pair of Wilson Benesch Torus subs and REL S/510s with the German Physiks. I would not have sold the subs if I thought the speakers were lacking in bass. I can totally see how one can be skeptical when looking at the numbers, but as they say, proof is in the pudding ... or listening in this case :)

BTW, do you still have the Rockports? Amazing speakers ... I’ve heard them many times and feel they’re a cut above Wilsons or Magicos. Color me envious :)

@arafiq 

It’s great that your speakers are fantastic without subs. You hear a lot how hard they can be to integrate. Would love for there to be a dealer here in Colorado to hear them. 
 

Yes I do still have my Avior ii’s. I auditioned Wilson Sasha DAW and Magico S5 along with the Rockports and the Aviors were the clear winner. They will be with me until the end. 

 I'm not sure I would say "zero chance", because a) folks who exclusively listen to acoustic music at sensible volumes may be well served by single-drivers, and b) as @arafiq says, some single-drivers are said to outperform 3-way speakers. Lowther and Voxativ also come to mind, though tbh I've never auditioned either of them. 

@devinplombier A friend of mine locally has been messing with 'full range drivers' for the last 25 years. I've heard a variety of them at his house and in my shop as a result. Most of them sound just fine as long as you don't push them too hard. All of them fall flat on their face if you try to play anything with energy (with bass in it) at higher volumes. 

So I've heard Lowther, PHY, Voxitive, Fostex, Tangband and Cube; several different models from each brand. 

If you really want to get the most out your investment in such drivers you'll make sure they don't have any bass excursion on them by using some kind of crossover. IME a better way to do that is by placing a small coupling cap in series with the input of the amp driving that speaker. That way the amp has the same benefit. 

You might be able to find a woofer that is in and of itself has enough inductance to roll itself off as frequency rises, without the need for an added capacitor/inductor/resistor.  For me, the best single driver speaker is an ESL. And yes, they lack bass too.

Not exactly what you are looking for, but PureAudioProject speakers sounds like a single driver but with plenty of super quick and natural bass.