What creates the effortlessness in sound reproduction?

All good points Doug. Many of us don't listen above 75-89db average weighted C when off the leach!

Effortless sound comes with a proper amplifier match to a given set of speakers.  
Obviously HE speakers need the least amount of quality power to deliver fast, responsive effortless sound without strain.  
Yet typical low efficiency dynamic box speakers can also sound effortless with the right amplifier.  
My 86db large british monitors sounded exceptionally dynamc and effortless being driven by a high current Bipolar transistor amplifier with 300 WPC.  The results were literally startling.  

I think a system's perceived effortlessness can be achieved by a judicious application of effort.

@douglas_schroeder --

Peter is above board. The shameless ones are those with ulterior agendas.

Even without hearing the speakers he linked to I can see that they have many of the criteria necessary to achieve effortless sound reproduction - given the proper electronics and cables ahead of them.

Larger drivers, extended frequency response, plenteous power, overbuilt x-over or active x-over, larger speakers well past 4’, etc. Many speakers have a few of these traits, but this one he linked to seems to have the necessary attributes to create the effortless sound discussed here.

I have reviewed larger Legacy Audio speakers for Dagogo.com, such as the V and the Valor, and these are fundamentally superior in creating the sense of ease and capability beyond the norm. So, Peter’s link is not just shameless promotion, it’s a snapshot of the characteristics in a speaker that lend themselves to "effortlessness".

Btw, it seems the speaker uses a 12" mid. Those with discernment might look to see that also Legacy’s Valor similarly uses prodigious midrange. Why is that? Because it is fundamentally superior. Period. End of discussion. Size matters, and big gets fundamentally better sound in the end. Sorry for budget audiophiles, but that’s the realty.

Now you know. :)

Indeed the size of speakers/transducers matter, but sadly large size and high sensitivity is often dismissed, no doubt partly due to size costing obscenely much these days with refinement being taken to ridiculous lengths and putting the price of small standmounts into 10’s of kilo-dollars (imagine where that leaves their grander brethren on the price scale).

And yet, where price is no issue it seems a fortune is generally rather invested in moderately sized speakers instead of letting physics have their say; sometimes it even appears as if physics to audiophiles, certainly in regards to speakers, is tangential to the importance of belief for an atheist.

Interestingly, but to no surprise John Atkinson of Stereophile "wriggles" his way around the question of large speakers as well:

https://youtu.be/QWU2sUnW-eM?t=1344

It’s worth mentioning that size (i.e.: air radiation area) is achievable via other means, namely from acoustic transformation as well - also known as horns. To boot this is the most effective way into high efficiency, you’ll have similar or more impact with less cone area (with all that entails in regards to inertia), and the coupling to the air is more effective in ways not only translatable into higher sensitivity. Of course, when we enter the region of bass the laws of physics dictate very large to monstrous size horns, depending on the specific tune and how low one needs to go.

Headroom is certainly paramount where effortlessness goes, and to my mind powerful amps are in vain if the speakers aren’t properly efficient to convert that power into actual SPL without strain and thermal compression (save active iterations like larger ATC’s). Realistic dynamics requires more than one would think. There’s also SET’s and how they provide that elusive flow/liquidity and ease to the sound (which, for full effect, requires high efficiency speakers - in effect mostly horns). Class A amps in general, incl. SS designs, appears to have that ability to some degree as well.

Thinking about it certain speakers are inherently ’easier’ to listen to than others, and this may be related to timing aspects in particular; music somehow presents itself more simply, relatable and genuinely via some speakers, as if the brain is working less overtime trying to stich together the sonics into a coherent whole. Listening to Synergy horns be Danley Sound Labs only confirms this..

GeoffKait has it right.  Its not about drivers, efficiency, box type, ported/not, amp type- it's about the ability of all the system elements (from source to speaker) to cover the dynamic range of the source and at the level you want it to play and STILL have significant headroom (distortion free power or SPL to spare).   So lots of combinations of drivers, box types, amp types can sound effortless.  It's how you combine and match elements-what goes with what-that becomes difficult to achieve.  

A combo of amp and speaker may work but it has a SPL limit until some sort of clipping/limitation (preamp input overload, amp clip, speaker break up, etc) occurs.  One SPL level can sound effortless but a small increase of just 3dB (3dB louder requires twice the power) clips the system.  Your ear detects extremely small amounts of distortion.  Real music can have huge swings in dynamic range (real life can have a 60-70dB above ambient level dynamic range).   Maybe a gigantic live PA can cover that, but not a stereo system.  That's why we all say larger power amps generally make our systems sound better, we gain dynamics.  

That's why some of us swear by high efficiency speakers: suddenly our system has more dynamic range with the amp we already own.  I know a Klipschorn was the first time I ever heard dynamics and it was a revelation!  High efficiency speakers often have qualities some of us don't like, like limited dispersion (horns), or poor bandwidth, but we often live with those issues to have the dynamics.  Nothing wrong with that choice.  This is exactly what a speaker designer does, trade off one benefit to gain something else.  A clever designer can address weaknesses by designing in an application.   Klipschorn corner horns for example:
1) super efficient horn (addressing improved dynamics from very small amplifiers),
2) appears to cover more listening area situated in a corner (addressing horn limited dispersion) and
3) couples the speaker to the corner for bass boost (addressing horn limited LF bandwidth).  

Brilliant engineering example balancing everything to achieve real life higher performance! 

Brad
Lone Mountain