Trained ears.

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..

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.