How does solo piano help you evaluate audio gear?

So, most comments are correct about female voice, piano, and organ.

At my shop, we would close the door at the end of the day and take out our instruments and see if what we heard from the 50 or so speakers we sold was anywhere CLOSE to the live instruments.  Our competitor in Miami decided to become a recording person and worked very hard for years with excellent equipment to record and then playback a range of live performances in various venues.  Although he and I may disagree about some things, in MY shop the most accurate reproduction of the live instrument sounds and female voice (we had an electric piano, so unfortunately not able to do that, but our competitor spent months trying to get the most accurate piano recording possible--it ain't easy no matter WHAT OR WHO says it is, sorry.  If you think so, go try it and report back.  Otherwise, sorry, but you are ill -informed about the facts, which I know are not popular today as people tend to make up their own.

What we found after many, many sessions, was that if you wanted to hear exactly what you recorded, you needed SUPERB electronics and Magneplaners SET UP CORRECTLY.

SO, we sold a lot of Maggies and some super electronics--they are expensive and not for everyone.  Back then Audio Research was the winner, but things have progressed and I am sure there are others who are just as good today, although I would guess some of their stuff is still SOTA.  Certainly their pre-amps, which were always considered the best from the SP-3A1 on, still are at the top of the list for their better models.

Point is, boxes distort.  Such famous inventors as Bob Fulton and Mark Levinson tried to make hybrids with Quads, RTR's (electrostats), ribbons, huge woofers (Hartley 24's, etc) and so forth.  (Full disclosure: we built stands and cabs for some of Levinson's HQD System on contract.)  Phase issues were incorporated into mediocre speakers by B&O and better ones by Wilson and others, etc.

At the end of the listening process, side by side, none of these noble efforts eclipsed Maggies on piano, female voice, or organ for accuracy.  

Cheers!

@hilde45  Thanks for your comment.  No longer a dealer, but found these facts when I was in the '70's-80's.

Not "arguing" with anyone, but some posters here seemed to doubt that recording a piano was difficult.  I wanted to make it imminently clear that IT WAS, period.  This is a fact, not "made-up", so that was my goal.  Sorry if it came across as too harsh, but these days it seems even seemingly reasonable people tend to invent their own facts.  

As for Maggies, have your dealer set up a pair in YOUR ROOM (caps on purpose) and if your HW is superb, you will hear music.  If not, either try more accurate HW or, if you still do not like them, buy what you like.  We had 20 brands of speakers and I sold ALL of them.  I was running was a business, not a charity or a church, so I did not preach.  If you wanted to try Maggies, I brought them out and set them up for you.  If you did not like them, and many did not, I sold you what you liked.

My point here is that we found the most accurate reproduction of well-recorded piano, female voice, and organ on Maggies (driven by Audio Research gear) in those days.  They still are, in my opinion, the most accurate since all boxes distort and horns belong on the top of poles at high school football stadiums.

BUT, with @300 speaker manufacturers around at any given time, you pays your money and you makes your choice, as the cliche goes.  I sold you whatever you wanted; that does not necessarily mean you got accurate music reproduction.

Cheers!