Trained ears.

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 be....in 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..