Can a great system make a mediocre recording sound good?

A poor recording will always remain as such. What you get with a better balanced system is that even a poor recording would have a meaning. No it will not sound good but it would be easier to follow.

Thanks very much!

You explained it better than me...

I never spoke english only read it and i read only science or philosophy, it is why my expression is "square"....

The better your system is, especially imaging, the more it will reveal the great, good, bad, ugly.

The more you experience excellent imaging, the more you are aware of problems.

Yes it is true also in my experience...

But it is true not only with imaging,but with all other acoustic characteristic...

For example if your system give you a good listener envelopment, in some well recorded album you will be AMONG the musician on the scene...They may be around you... It will not be the case in heavily compressed music... It will be horrible... But what is hoorible on a bad audio system, stay bad on a good audio system but can become "interesting" because it take a new acoustic  meaning ... You "see" more...

I find it to be opposite. My really good system makes bad recordings almost unlistenable, It will make average recordings some better some average.

Our perspective are not exactly the same, but it is related also to the genre of music we listen to...

Most of my bad recordings in jazz or classical are more listenable in my system even if they stay bad...

But pop or rock may be exception.... The jimi Hendrix two albums i refer above are unlistenable because of compression...the mix in studio is horrible work...I hate too much mixed in studio music... I prefer natural instruments in natural acoustic room with minimal mix ... 

There's a reason why the epithet "forgiving" is quite high up there in the audiophile vocabulary.

In a poor recording a system can't reproduce something that is not there. An "accurate" system will play the good and the bad. It is not designed to fix the bad just reproduce what is in the recording.