Top two most important sound qualities

Fright and goosebumps 

1. Extremely low noise

2. Accurate tonal balance

@bdp24 

Most loudspeakers sound comically "small" to me, the image of a grand piano, for example, being reduced to a miniature of it’s actual size.

Good point. I guess we don't expect lifesize image from HiFi because 99% of the systems we have ever heard don't have it. 

I graduated from bookshelf speakers to floorstanders and then 15  inch dual concentrics and whilst each one got better in this regard none of them have life sized imagery.

@panzrwagn 

Effortlessness - that sense of ease that allows you to forget about the hardware and just hear the music.

That's another easy one to forget.

Real music doesn't sound forced or strained but many systems do.

You probably need the right combination of loudspeaker and amplifier to get that sense of ease.

Usually that means bigger and more powerful.

Tonality, clarity, sound staging/imaging. In that order. 

@waytoomuchstuff 

Did you ever see the South Park episode blasting Stevie Nicks' voice? Hilarious