Quite late to this party but here are my thoughts on this issue:
1) Truly live dynamic effect from reproduction requires not only high sensitivity but drivers that don't have an early onset of compression, either from mechanical or thermal effects. High sensitivity by definition means that the driver is very responsive to small inputs, which has great benefit for the retrieval of low level information and subtle "micro-dynamic" shifts that get glossed over by most speakers. These micro-dynamic shifts we hear readily live and it is a key signaler in the "live" feeling along with sudden macro-dynamic shifts that are not blunted or rounded off.
2) The problem with low sensitivity drivers (cones in particular but also ribbons...electrostats seem to behave differently) is that they are not very responsive to small inputs. This is due to mass, magnetic field strength and mechanical resistance to motion. The combination of these effects results in a driver that needs significant energization to move. This means a lot of micro information will be smoothed over or diminished in importance. This reduces the "live" feel and has nothing to do with the raw power of the amplifier driving it. On the macro end, low sensitivity drivers will, once sufficient current is flowing through them, have significant thermal effects where the onset of thermal compression sets in. Lest you think this can happen only with sustained high power, you are not correct...a driver will heat up very suddenly with dynamic peaks and effectively truncate those peaks, thus reducing their impact and "live" feel. This also cannot really be overcome with more power because the driver itself is LOSING sensitivity as it heats up. So, rather than getting 3db with every doubling of power you might get 2db or 1db or even 0db increase with a doubling of power...just an increased likeliness of burning out a driver.
3) Electrostatic speakers behave differently from ribbons and cones. It has been my experience with numerous electrostatic speakers (STAX, Audiostatic, 3x Acoustat) that even though they have low electrical sensitivity, they are still quite responsive to small signals, perhaps because they have relatively low mechanical resistance to motion. This means that they do very well at quiet volumes to mid-high volumes. Micro is well preserved as are tonality and spatial cues. With heavier foil they also will produce quite substantial bass (large panel of course). The STAX ELS-F81s I had were some of the best low level speakers ever, perhaps due to have a very thin 4 micron thick film...exquiste with small music at moderate volumes. Also, unlike cones, they do not heat up so there is not a significant thermal compression issue...however, there is a significant mechanical excursion issue that limits dynamics, which is why the bigger the panel the higher the dynamic range normally (ironically also the higher the sensitivity). So, really big panels can do macro quite well (with a thicker foil of say 10 microns) and do micro quite well...smaller ones only do micro well. This can give a significant "live" feel for smaller ensembles but not really for the big stuff.
4) Magetostatics need juice to wake up due to heavier foils and relatively low magentic strengths and have the same excursion limits like electrostats...the lighter the foil the better they will be at low levels (or stronger magentic fields). If a ribbon can be made high sensitivity using Nd magnets then they can have superb dynamics both micro and macro (up to excursion limits). Standard low sensitivity ribbons will be somewhat lifeless for micro at normal volumes, necessitating "turning it up" to get the low level stuff out...like low sensitivity cones. High sensitivity ribbons (like tweeters) can be SOTA for dynamics and "live" feel. Only Apogee of Australia has made a somewhat high sensitivity full range ribbon...I would love to hear it as it could be a dream speaker. Just like cones, magnet strength and mass matter and a high sensitivity ribbon will beat a low one any day of the week for "live" feel.
5) Complex crossovers eat power. The complex crossovers that most large, multi-way, speakers employ waste power and introduce a lot of reactance to the overall circuit that a lot of amps (especially those with global feedback) don't really like. This will impact power delivery, phase and distortion that will affect "live" feel of the sound.
6) Single driver "full-range" drivers...well they are not really full-range unless loaded into a long horn, which has it's own potential issues. If not in a horn they are lively and give good "live" feel for micro but are limited macro and in bass. Used as a mid, like in Horning, seems to be a not bad use for them and then with minimal crossover (see 5) and other high sensitivity drivers to make a good 2 or 3 way system that will do well with micro and macro...perhaps not the ultimate in "live" feel but interesting. Speakers here are around 95-100db/watt
7) Smaller 2 or 3 way horns. Simlilar to 6 but with better "live" feel potential if good compression drivers with well designed horns are used. Cleaner micro and somewhat higher macro "live" feel. Easier to make coherent than larger horns (I will get to that soon), which helps with "live" feel for the music range they can handle. Bass is limited and can reduce "live" feel to some bass needy people. Adding a sub is tricky though. One of the easier speakers to get "live" feel from micro to macro with exception of really large musical works due to good driver integration. typically sensitivity here is 95-105 db/watt
8) Large, multiway horn systems. They have the highest potential for both micro and macro "live" feel but also the highest complexity and difficulty to get right. Despite the very high sensitivity they often miss live feel because of lack of coherence because of poor phase/time integration, which delivers a somewhat scrambled signal that no longer has that "snap" of live. This, btw., is also an issue with multi-way cones in addition to their lowish sensitivity. A mid-sensitivity speaker can have a lot more "live" feel than a big horn if it has a very good Phase/time integration (Thiel CS3.7s come to mind and Vandersteen 7s). However, get the phase/time integration of a big horn right and it will surpass the rest. BTW, that integration is also part of what helps large full-range estats to have a good "live" feel up to their limits.
This last point is overlooked by those who don't think that phase/time coherence is important in audio reproduction but I think it is vital in getting "live" feel along with high sensitivity. You CAN get reasonable "live" feel with a mid-sensitivity, time-coherent speaker...Ref 3a, Thiel and Vandersteen can do this pretty well...to a point...it cannot take it to the point of a big electrostat or mid-sized, time coherent horn or especially a large scale horn that has been carefully phase/time integrated.
1) Truly live dynamic effect from reproduction requires not only high sensitivity but drivers that don't have an early onset of compression, either from mechanical or thermal effects. High sensitivity by definition means that the driver is very responsive to small inputs, which has great benefit for the retrieval of low level information and subtle "micro-dynamic" shifts that get glossed over by most speakers. These micro-dynamic shifts we hear readily live and it is a key signaler in the "live" feeling along with sudden macro-dynamic shifts that are not blunted or rounded off.
2) The problem with low sensitivity drivers (cones in particular but also ribbons...electrostats seem to behave differently) is that they are not very responsive to small inputs. This is due to mass, magnetic field strength and mechanical resistance to motion. The combination of these effects results in a driver that needs significant energization to move. This means a lot of micro information will be smoothed over or diminished in importance. This reduces the "live" feel and has nothing to do with the raw power of the amplifier driving it. On the macro end, low sensitivity drivers will, once sufficient current is flowing through them, have significant thermal effects where the onset of thermal compression sets in. Lest you think this can happen only with sustained high power, you are not correct...a driver will heat up very suddenly with dynamic peaks and effectively truncate those peaks, thus reducing their impact and "live" feel. This also cannot really be overcome with more power because the driver itself is LOSING sensitivity as it heats up. So, rather than getting 3db with every doubling of power you might get 2db or 1db or even 0db increase with a doubling of power...just an increased likeliness of burning out a driver.
3) Electrostatic speakers behave differently from ribbons and cones. It has been my experience with numerous electrostatic speakers (STAX, Audiostatic, 3x Acoustat) that even though they have low electrical sensitivity, they are still quite responsive to small signals, perhaps because they have relatively low mechanical resistance to motion. This means that they do very well at quiet volumes to mid-high volumes. Micro is well preserved as are tonality and spatial cues. With heavier foil they also will produce quite substantial bass (large panel of course). The STAX ELS-F81s I had were some of the best low level speakers ever, perhaps due to have a very thin 4 micron thick film...exquiste with small music at moderate volumes. Also, unlike cones, they do not heat up so there is not a significant thermal compression issue...however, there is a significant mechanical excursion issue that limits dynamics, which is why the bigger the panel the higher the dynamic range normally (ironically also the higher the sensitivity). So, really big panels can do macro quite well (with a thicker foil of say 10 microns) and do micro quite well...smaller ones only do micro well. This can give a significant "live" feel for smaller ensembles but not really for the big stuff.
4) Magetostatics need juice to wake up due to heavier foils and relatively low magentic strengths and have the same excursion limits like electrostats...the lighter the foil the better they will be at low levels (or stronger magentic fields). If a ribbon can be made high sensitivity using Nd magnets then they can have superb dynamics both micro and macro (up to excursion limits). Standard low sensitivity ribbons will be somewhat lifeless for micro at normal volumes, necessitating "turning it up" to get the low level stuff out...like low sensitivity cones. High sensitivity ribbons (like tweeters) can be SOTA for dynamics and "live" feel. Only Apogee of Australia has made a somewhat high sensitivity full range ribbon...I would love to hear it as it could be a dream speaker. Just like cones, magnet strength and mass matter and a high sensitivity ribbon will beat a low one any day of the week for "live" feel.
5) Complex crossovers eat power. The complex crossovers that most large, multi-way, speakers employ waste power and introduce a lot of reactance to the overall circuit that a lot of amps (especially those with global feedback) don't really like. This will impact power delivery, phase and distortion that will affect "live" feel of the sound.
6) Single driver "full-range" drivers...well they are not really full-range unless loaded into a long horn, which has it's own potential issues. If not in a horn they are lively and give good "live" feel for micro but are limited macro and in bass. Used as a mid, like in Horning, seems to be a not bad use for them and then with minimal crossover (see 5) and other high sensitivity drivers to make a good 2 or 3 way system that will do well with micro and macro...perhaps not the ultimate in "live" feel but interesting. Speakers here are around 95-100db/watt
7) Smaller 2 or 3 way horns. Simlilar to 6 but with better "live" feel potential if good compression drivers with well designed horns are used. Cleaner micro and somewhat higher macro "live" feel. Easier to make coherent than larger horns (I will get to that soon), which helps with "live" feel for the music range they can handle. Bass is limited and can reduce "live" feel to some bass needy people. Adding a sub is tricky though. One of the easier speakers to get "live" feel from micro to macro with exception of really large musical works due to good driver integration. typically sensitivity here is 95-105 db/watt
8) Large, multiway horn systems. They have the highest potential for both micro and macro "live" feel but also the highest complexity and difficulty to get right. Despite the very high sensitivity they often miss live feel because of lack of coherence because of poor phase/time integration, which delivers a somewhat scrambled signal that no longer has that "snap" of live. This, btw., is also an issue with multi-way cones in addition to their lowish sensitivity. A mid-sensitivity speaker can have a lot more "live" feel than a big horn if it has a very good Phase/time integration (Thiel CS3.7s come to mind and Vandersteen 7s). However, get the phase/time integration of a big horn right and it will surpass the rest. BTW, that integration is also part of what helps large full-range estats to have a good "live" feel up to their limits.
This last point is overlooked by those who don't think that phase/time coherence is important in audio reproduction but I think it is vital in getting "live" feel along with high sensitivity. You CAN get reasonable "live" feel with a mid-sensitivity, time-coherent speaker...Ref 3a, Thiel and Vandersteen can do this pretty well...to a point...it cannot take it to the point of a big electrostat or mid-sized, time coherent horn or especially a large scale horn that has been carefully phase/time integrated.
