How does solo piano help you evaluate audio gear?

@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!

@richopp Clarification understood and appreciated. It seemed pretty clear that recording a piano is difficult, so I was a bit confused by the energy you put into your rebuttal. But we agree! Cheers!

A fact not mentionned here with the importance it has :

No audio system and speakers will sound the same in two different rooms...

A controlled and treated room will give to an audio system his real potential S.Q. and this potential S.Q. will have NO RELATION to the same system in a non controlled and non treated room...

Then the best way to listen to any instrument recording in a chosen system is to model the room with his dynamical zones pressures accordingly not to the "measured by tool " specs. of the speakers but accordingly to what your ears will say to you in this progressively TUNED room one step at a time...

Then you will listen the  specific "recording" of an instrument and you will discover that not one piano recording sound the same on different system but ESPECIALLY in different room... Then chosing some voices and instrument to chose gear is possible like proposed by the OP but in a non treated room and in a non controlled room this have his limit...Acoustic is more powerful than MOST change or upgrade  of gear in improving sound...

I chose my speakers by reading for months reviews and i did  the same for my amplifier and for my dac...I could not listen before chosing any piece of gear where i live...

When i listened to them in my non controlled room i was not displeased but not pleased either... 😁

BUT when after buying them i modelled my room with acoustic devices and treatment for this specific  system i owned now, i reach a level of S.Q. which had no relation with the original sound of this system in my plain room, no relation at all, NONE...

Then i know the OP asked another question than the answer i give in this post, but people must be conscious of this fact...

Acoustic is the key to high fidelity not the gear choice by itself...

Be it magneplanar or my Mission Cyrus speakers, or any dac compared to mine, or My Sansui versus any good amplifier....

The bad news is they will be all different in S.Q.with plus and minus...

The good news is this difference between gear DECREASE very much  versus the difference between plain room acoustic and fully controlled room adapted to each system itself...

Then magneplanar or box speakers it is possible to be happy with any of these two and forgetting  any future  upgrade if we use acoustic rightfully...

It is possible because the same room must be controlled in a different way completely with magneplanar or with my box speakers...If someone know how to do it with his tuning ears the results will be happy for the two type of speakers... Different but very good... I know because my friend own magneplanar and me box speakers...He is a magneplanar addict and guess what was his surprize listening my small box speakers in my controlled room ?

Then dont trust sellers, trust acoustic science and your ears using it....

It is very easy to buy good gear anyway, but less easy to learn how to treat a room and control it FORTHIS SPECIFIC GEAR AND FOR YOUR OWN EARS...

My best to all and i apologize for being beside the question of the OP...

this may be relevant to the discussion - most would agree that voice is critically important...

https://www.cnet.com/tech/home-entertainment/insanely-great-the-harbeth-40-2-monitor-speakers/

Piano has stretched overtones.   I believe it is somehow related to the fact that string has mass.  Extremely long and thin string under extremely high tension would have straight harmonics, but it is not practical.  Because of this stretching piano octave is not tuned to double frequency, but a little bit higher when the beating with overtones of lower octave stops, resulting in about 30 cents error at both ends.  That is why tuning of the piano is so difficult and also why reproduction of the sound is very difficult as well.  Any harmonics produced by the playback system might beat against stretched piano overtones.  Overly warm systems produce even order harmonics that sound great with other instruments or voice, but piano sounds almost like out of tune.