M30, c7es3, shl5 .....
OK, I think I understand the issue that you can't compare these models side-by-side under demo conditions although you would like to do so.
As I have said here before, I do not have hi-f at home because (a) I'm always working so not really any time to sit and relax to music (b) I don't want to be seduced by my own creations. So, as you may have read from Newsletter 23 I was fortunate indeed to spend time earlier this year travelling in the Far East. And in particular, when I was at Tropical Audio in Kuala Lumpur I made just the comparison you are interested in: M30 v. SHL5 v. C7ES3. Actually the M30 and C7ES3 were side by side in the front listening area, and the SHL5 in the back room - some pictures in the Newsletter, others attached.
Now, even though I designed all three of these speakers over about a twenty five year period, I don't think I have ever actually compared them under 'customer conditions'. I've probably made short comparisons in the lab during their development just as a sanity check that I've not lost the plot and gone off on a wild tangent but that's not quite the same as hearing them as you, the user would. And Sam Chan, the owner of Tropical Audio who I blessed to know, has an opinion on sonic matters which I'd be foolish to disregard.
So, when I heard the M30 v. the C7ES3 in his rather lively room (and this is a significant point) I'd say that the C7ES3 was slightly more "immediate" where as the M30 was slightly more "relaxed". Which is right? Which is best? Well, that's impossible to say outright. As for the SHL5 in the other room (v. some full range electrostatics) the SHL5 could handle much more power than the 'stats, had a much more solid and credible bass, and were at least as clean in the middle frequencies leaving me with the definite question "what is all the fuss about with 'stats when a good dynamic speaker is smaller, more convenient, has better bass and no long-term degradation issues?"
And now the SHL5 v. M30 v. C7ES3: to my ears, what surprised me as only an occasional listener to hi-fi was how similar in character the M30 and SHL5 are. They are very similar in the middle frequencies although, s you'd expect, the SHL5 has a little more bass due to the bigger box. The C7ES3 is a little different: equally sweet but the image is perhaps a row or two closer to the performer, or at least that's how it seemed to me.
Unfortunately, perhaps due to the highly specific and emotive language surrounding loudspeaker evaluation Sam and I were not exactly able to cross-translate our feelings, and even so, those feelings could reverse from preferring one speaker to another when the music changed.
So what did I learn from this fresh experience with my own loudspeaker designs? First, there is a market for all three depending upon user's taste. There is no overall best one amongst them. So much depends upon how you think performers should appear in front of you. Second, we must factor in the room's acoustics. If your room is well damped (curtains, floor mats etc.) then that may well swing your preference. What I can say is that the C7ES3 was designed in my back-bedroom which is very well damped because of all the books etc., my musical selection when designing the C7ES3 was a good helping of pop, rock, jazz and blues and that it sounds open and clean.
We could discuss all day or all year long 'which is best' but the answer has to be whichever is best for your ears in your room on your music. Final comment: all three models feature the exclusive Harbeth RADIAL™ cone material. Once you have spent an hour or two* listening to your music on these speakers, switch back to your conventional speakers and you will be shocked by how foggy they sound.
*One of our highly regarded dealers told me recently of a husband/wife, both professional musicians, out auditioning speakers. They'd listened to and rejected all the brands you'd assume to be in the same pool as Harbeth. He told me that within ten seconds of listening to the Harbeths they both agreed it was the sound for them. I'm so familiar with what RADIAL™ delivers that I take it for granted but it astonishes me how some folk seem untroubled by clarity and focus on peripheral matters like deep, deep bass or super high efficiency. To me, naturalness, clarity and transparency are what hi-fi is all about - that hairs on the back of the neck 'close to being there' experience.
Alan A. Shaw
Harbeth Audio UK