I guess what he means is the speaker plays such an important part in the reproduction of music in the home that if you want to get as near to the real thing as possible then in his opinion, those types of loudspeaker will get you there the closest.
I guess so.
However in my experience the "realness" depends very much on the recording. E.g. I have a CD copy of a recording made by a friend of Gregson and Collister made (with permission) in a pub. This has added character (as SG puts it) due to the microphone, open reel, A/D process. However it has no deliberate compression.
It sounds very convincingly real on lots of systems!
It it also difficult to listen to for any period of time... because it sounds too real.
Thankfully 99.9% of my music collection has been processed and compressed to make it sound much nicer, albeit less real.
I can understand why some people like the sound of horns because they seem to "uncompress" the music and make it more real. A bit like my G&C recording though, I don't find this satisfying over the long term.
I can also understand why people think box speakers sound boxy. IMO this is because of the way they produce low frequencies. However, they don't all sound boxy e.g. some mini monitors, Kudos Titans.
So what should we listen for?
Actually I don't hink we need the ramblings of SG to tell us. Judging from the other replies we know what we like and what compromise we are aiming for.
For me, I want a sound that is relatively neutral and I can therefore listen to a wide range of music and at different SPLs depending on the time of day and my mood. The most important thing for me is for the music play in time and in tune and to communicate the interplay between musicians - that's what enables me to become immersed in the music.
Sounds simple, but it seems not to be. >90% of the systems at the Munich show were fairly hopeless in this respect. FWIW, the WE horns and the Vox Olympians fall into the >90% category for me.