Trained ears.

Simple question, which may have a non simple answer.
How does one train one's ear for evaluating Hi-Fi equipment?
The emphasis primarily on loudspeakers but other Items along the chain to the wall socket can be (and should be) Included.
I am a qualified Pianoforte Technician so I can tune a piano, but I can't tuna fish.....
I've never thought of myself as having 'golden ears' to evaluate equipment.
Thoughts/Tips/Views please.

RIP- Jacques Loussier...
In your case it should be pretty simple - use well recorded piano music that you know well and ask yourself which system or change gets closer to the sound of a real piano in a real room

in my case And given the types of music I am most experienced with I use a variety of rather sparsely recorded folk music and look for system changes that get closer to the experience of real musicians in real space. 

Listening for gross frequency response issues or the top and bottom of the range is besides the point if the system is messing up the small details
Complicated. First of all I try to figure up what annoys me most in what I hear and then go from there. Drive flow and coherence are what should be done right before everything else, I believe. Assuming that speakers are more or less okay, this means that you start at the source. And the best source is tape.
Agree with the above posts, plus sitting in the sweet spot with eyes closed helps quite a lot. Also, if you wear glasses, remove them.

I agree with all above posts.  Listen to music that you are familiar with (or that you like and are going to listen to over and over).  Do the instruments sound real?  I’ll listen for drums...high hats / cymbals.  

Familiar music is key, critically listen, close your eyes.  

If everything is right, or close, you can go from critically listening / evaluating to just getting lost in the music.

If you’re trying to see what differences a wall outlet or power cord makes make sure to change only 1 thing at a time.  Power cords and outlets / power conditioners increase bass depth and weight, gives a darker background from which music seems to just appear and gives better highs in my experience.

It’s all system and synergy dependant but changing out pieces and then evaluating the difference is part of the fun.
I wonder if people really learn to listen.  I was mesmerized the first time I heard my uncle's JBL Paragon/Mac system back in the 60's.  My father owned EV400 and an HK receiver and I was constantly listening until I was old enough to buy my own stuff.  I think you either relate to hifi or you don't.  I guess you can learn to hear what system comes closer to a live piano, assuming the recording is remotely trying to accurately reproduce the piano.  But ultimately, I think it's a more visceral, subconscious thing that listening to a great system does. 
Just like athletes who have to trainrf their bodies, critical listeners need to train their hearing.  Wide exposure, frames of reference, concentration, attention to detail...repeat, repeat and repeat.  No different than how a wine sommelier or perfumer train their senses. It takes both an interest and a commitment.  
If you know the sound of live, acoustic instruments, it's not that difficult to evaluate audio components ... especially if you have a few recordings that you've made yourself.
If you are comparing equipment, use familiar music, and do an ABA test.  When you go back to the A after listening to the B, you'll really hear any differences.

Good advice as above. A piano is both melodic and percussive in nature.
Test these characteristics with familar music, passages, for accurate texture and timbre when evaluating electronics. Ask yourself, "does this music reflect the live event"?  Possessing the ability to tune a piano requires an awesome ear. You already have an awesome ear. And yes, you can't tuna fish.  Enjoy the music and have fun.

Happy Listening!
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If you can tune a piano, then you know what the notes should sound like.

Just listen to as many systems as you can, and form your own opinion.

You hear pitch with exquisite precision because you understand the concept of pitch extremely well. Okay. So what's your understanding of grain? Attack? Decay? Ambience? Sibilance? Harmonics? Timbre? Timing? Presence? Palpability? 

I'm no piano tuner, but pretty sure you could write volumes on pitch, tension, humidity, fundamental, harmonics, etc. Some of what you're familiar with you will be familiar with here. A lot of it will be new. Doubt you've spent much time listening for grain. No piano ever made was grainy. Grain is an artifact of the recording-playback chain. Just one random example.

I was once like you, in that having played musical instruments I was pretty good at pitch and tone. Yet I couldn't tell one CD player or amp from another to save my life. Now, no problem. Takes a while, but you can learn.

If you really do want to learn here's the best help I know of:

Robert Harley clearly covers not only all the equipment, but how it works and how to evaluate it including how to listen. Whole chapter devoted to how to listen and why and what to listen for. All the terms. Been out forever but updated and so well done that even my 30 year old copy is still worth reading.

There is the classic book by Alton Everest called Listening Skills for Audio Professionals.

More recently, Jason Corey has written an excellent book which is complemented with online training by the author.

And before you ask, Yes I am trained. And Yes, training makes a night and day difference. Critical Listening requires training. Those who listen to music daily are like frequent flyers. They have been to many places. Can they land a commercial jet at SF airport - Absolutely Not - they are just armchair amateurs.
Thanks for all the great advice chaps!. I did borrow a reel to reel tape deck with my bands music that we recorded in a studio as well as recording my own piano at home, a longgggggg time ago. The sound through my Impulse H1's Horn speakers was really good at getting all the nuances of the band and especially my own home piano at the time with all its quirks which I recorded. I should have recorded just  the 4ths and 5ths or major 3rds and 6ths on the piano and then played it back to see if I could hear the 'beats' of two notes not in unison with each other, as the only pure notes are each note itself if there is obviously 2 or more strings to each note or octaves, everything else is tuned 'off'. That would have been a good test for the loudspeaker, or any speaker!
I can record my piano, drum kit and synth with my Yamaha AW4416 mixing desk, I only need to buy some microphones. I would be pushing my luck by buying a reel to reel at present, lol.  Thinking about my buddy who is in Germany now probably still has the reel to reel tapes of the band.Hmmm.....
I think I know 'The Wall' by Floyd the best probably musically and when the vinyl album was played with my H1's, with an LP12 TT and a pair of tube Audio Innovation 1000 mono block power amps and Audio Innovation pre amp, was a totally awesome sound to my ears.

I’m a new audiophile but have always admired and recognized quality playback from the time I was a kid. I have a couple of thoughts in this matter based on what I’ve learned over the last 5 or 6 months that I’ve been into this.

First, all the advice above is good, of course.

Second, don’t worry about what other people like or say. I’m not saying not to accept wisdom and experience and good advice. Just don’t think you have to like what someone else says is good or feel bad about what someone else says is bad. It is about pleasure and entertainment.

Third, even without golden ears you should be able to differentiate some level of good vs bad. The first time I heard my system after it was properly set up I recognized its lushness, richness and clarity immediately. I could not have described what I was listening to but I knew it was good. Big Mac vs Bistecca Fiorintina (grilled slab of marbled Tuscon porterhouse briefly introduced to a searing open fire). Boone’s Farm Tickled Pink vs Amarone’ from Venice.

Fourth, as mentioned above, listen, listen, listen.

Fifth, don’t feel like you have to be an expert. Unless you want to be. Don’t feel like you have to hear every nuance, every system, etc. Unless that is you goal. Find out what makes you smile. Find out what makes you want to spend time in front of your system. Find out what gives you goosebumps or brings you to tears (in a good way). Those two might be the most important of all. Who cares if you can’t explain why it moves you, as long as it does.

Having said that, the more I listen the more I’m able to articulate what is important to me. I’ve got a long way to go, but that can be part of the fun too.

Right now my priorities seem to be strengths of the system I have. Coincidence? Probably. But those things are: tight, precise bass with separation between kick drums and bass guitar/stand up. Lack of boominess and muddiness. Round, full, defined soundstage (but not fanatical about 3D effects, etc. High frequencies that are not too bright or glaring or tinny. Mids that are rich.

That’s all I got. Guess I'm a cheap date.
I am a die hard Horn Loudspeaker lover as they portray music as I like to hear it. having said that I heard some .7 Magnepans playing solo piano and that sound floated my boat very much. 
Well, because you mentioned him Jacques Loussier - Plays Bach on Telac is well recorded and can serve as a suitable reference...but references where you missed the original event ( or events w multi-track ) can be dangerous....

the points others have made about training, being trained and having an approach to learning are quite valid.

i refer to maximizing a system for a few references as flavor changing or tail chasing... I realized I was doing this... and I set off on a journey to better understand the chain., where things went wrong and finally trying to get back to the original event - that is for me the goal, elusive as that might making your own references   this is of course not trivial ... you can as some suggest go get high speed tape and or high quality digital. The zoom 6 digital recorder might be of interest to you in recording piano as a reference... I use on all the time as an adjunct to a much more complex mobile rack...

have fun and yes RIP Jacques... a consummate artist..
I was playing the Bach CD only the other week and it is superb sounding. JL wasTruly a great pianist. 
I will look into the zoom 6 digital recorder, its small and easy to slip into the house unnoticed. Thanks for the tip...

I heard a drum kit being recorded with a Roland BR600 little mixer just using the Internal mics of the BR600. Was Impressive Indeed.
Trained ears are overrated.  It can be mistaken for learning to speak/write like an audiophile.  Virtually anybody can hear differences in sound, but not everybody can verbalize what they hear.  If you know what a real instrument sounds like, then you have all the training you need to evaluate audio equipment and recordings.  It's not complex.
I agree that it can be taken too far. For me anyway. I do not wish to be come over analytical and I generally do not enjoy the time I spend listening to my equipment although some of that is necessary. It just not what I want my primary focus to be.

I can enjoy a song that i used to love way back when when it pops up on the oldies station while cruising through the country in my pick up with the windows open and that can be as meaningful and as enjoyable as an intense listening session with a high quality source of a moving piece of music.

I'm a bit of a gastronome and a fairly decent cook. But I can enjoy a can of Vienna sausages, a bag of Cheetos and a Budweiser too.
Anybody posting on this board is off the deep end....

but it if I am hunting or fishing, I prefer Landjagers, make them myself....

But yes, hopefully the listening is immersive and deeply and emotionally joyful....

there is a music section of the board here, what’s on your turntable tonight is my favorite...thread but there are others for CD, streaming, even live music. not so much gear and technical talk....late nite crazy marathon listening is the norm.....
What is complex is to tune the system like an instrument. You have a few components working together that must become the one. This does require experience and some knowledge in addition to hearing. And don't forget the room - it is probably the most important single component, provided the rest are good enough. One wrong set of cones under one component and the system is out of tune to various degree, wrong platform under turntable and it's no good, wrong or not quite right power cord on your Studer deck and something is lacking.
First make clear you have a balanced system. All music should sound eaually fine (or bad). The system should not favourize any specifical type of music. Make sure every recording you play sounds different. That you can hear differentiate between good and bad recordings. That you can separate individual instruments and singers and follow their lines. And that the transparence and dynamics makes you get a "live" feeling.
Then we have the question if it sounds correct. Play the piano someone says. I probably have a piano on thousands of recordings. No one sounds the same. What is correct? If it sounds natural it's ok. Only if you were there and did the recording yourself you would have a chance to know. 
Read between the lines. Lots of exaggerations when audiophiles discuss "huge" differences between dacs, amps, IC's whatever. In reality very small differences, maybe probable to hear if you really want to and are searching for them. Fun, but not sure if it really matters.  
Agree to all , N80 your number 4 is very very very true Listen listen listen listen listen, spend time listening, If you have two systems helps too....
When i began my journey on a another, enjoyable, frustrating, subjective hobby - wine -- i asked a great sommelier the same question. His answer: pop a lot of corks, and think abotu what you are tasting".
I learned not onyl to taste wine and what was good, btu more importantly what i liked and what it might do well with.
@gosta : You bring up a good point in regard to transparency. For me that was one of the first things I was really able to articulate about what made me like hi-fi SQ. With my system the speakers disappear. It does not sound like the music is coming from a component or machine, it is right there in the middle of the room.If you close your eyes you forget about equipment and to me that is right up there at the top of my list of important things. And I still forgot to mention it above........

This one is also easy to test and does not really require 'golden ears'. Put on a well recorded song, medium volume. Stand up. Cover your eyes. Spin around a few times until you are disoriented and then try to locate the source of the sound. It should be somewhere between and out front of your speakers.

@tomic601 :  "Anybody posting on this board is off the deep end...."

Agreed. And when someone sees you spinning around with your eyes covered pointing at empty space this is confirmed.
The n80 spin test as it shall now be known !!!!
freaking love it...

going to try it sober
@tomic601  :  "going to try it sober

Safer. But generally not as fun or revealing.