How close to the real thing?

"BTW, IMO people that buy audio equipment aren't heroes, people that engineer them are."

Well said Irvrobinson, but that only serves to prove my point. True heroes are self-effacing. Bravo!

When I was in a band (quite awhile back), I had the use of a studio reel to reel (can't remember which make) that I loaned to record my own piano in my house. The replay through my speakers (Impulse H1 horns) was close to the real thing on playback ( through the said speakers).
So 5% is way of (IMHO) to my own personal experience.
I would say IMO that we are up to 90%+, and if ones hi-fi can differentiate between different makes of Instruments, ie a Strat from a Gibson, a Steinway (the baby)from a Bosendorfer (the daddy) then that % maybe even higher.
Again, 5%? one may need to upgrade ones gear.

I wish that I could understand by what measure you guys are able to quantify realness. Is it information? IMO, realness is more than that. A high resolution photograph can yield all the empirical information of a direct viewing, but it's not the same, is it? We can go back and forth between the photo and the object and never be able articulate anything lacking in the photo. But still, it's less to me. I'm not saying that I've never been momentarily fooled by a sound coming from a speaker, especially when it comes from outside the plane, but to me, that's not nearly enough to make a case for realness. I suspect a system will alway's be limited, if only by the differences in the way that instruments and a speakers excite a room response.

I would like to hear the MBLs, but have never had the opportunity. Perhaps that fortunate, because I probably can't afford them, my room probably won't support them, and they are so ugly even my understanding spouse would have to call foul.

The step response you speak of, which is really a time-domain impulse test, is interesting, but I don't think anyone has ever shown a correlation between good sound and a perfect impulse test. As I recently posted in another thread, and just my personal opinion, I consider the use of first-order crossovers, necessary to achieve the perfect time domain performance the CS5's demonstrate, are just a marketing gimmick, and lead to more problems than benefits.

The Soundlabs achieve linear phase response because they are a single driver, have no crossover, so naturally they are good in the time domain, but does that really contribute to their great sound? I don't know, but I doubt it.

I was very tempted by the Soundlabs, but their trade-offs didn't quite suit me. And they're huge. But when the A1s are good, like on stringed instruments, they are most engaging speaker I've ever heard.

Live performances have a different dimensionality based on seating, hall ambiance, and all the little nuances that make it "real" to some. You can't catch it all in a recording. A guy that trips up the stairs, or a couple giggling a few rows back. These things make it "live" for us.

I think of it as analogous to watching a well done movie of a plane flying through Grand Canyon. If you watch it on your 20 inch Sony you are getting 10% of the experience, but if you watch it at Imax, closer to say 80%.

I've heard huge Rockport's or Verity's nicely set up that bring you very close to to live. I'm going with 80%