Can a great system make a mediocre recording sound good?

complicated subject, not strictly GI/GO but close enough to it to make finding a happy medium a protracted and almost [but not quite] Sisyphean task.  you need a system [not just a speaker setup but your equipment and room] that accentuates euphony in a useful way. in a large room, properly set-up Vandy 1Ci or 2Ce speakers will make harsh recordings sound markedly less harsh, at not a great cost to ultimate clarity, but NOT in a small room where one can't be at least 10' from those speakers with those speakers not further than 3' from any wall - in this circumstance poor recordings sounded shouty and harsh.  the local mag hifi stores found their vienna acoustics speakers big sellers for a similar reason, folks with money and big listening rooms found them to be mellow but clear enough, with a wide variety of music. these speakers didn't image quite as well as the vandys but had a somewhat wider sweet spot. the speakers i settled with, a pair of thiel cs.5 minitowers, struck a good balance plus are surprisingly forgiving of poor room acoustics/room dimensions, they sound generally on the sweet/mellow side of neutral, and they image excellently no matter what, with minor image width/density differences noted upon their degree of toe-in. my maggie SMGs also were among the more mellow sounding speakers i've had over a wide variety of music. they did not seem to sacrifice a lot of clarity in well-made recordings, on the best recordings they presented "another room within the room" type of reality, like their larger brethren. these speakers also did not require a big room, a typical spare bedroom was enough for them. 

I have to come down strongly as a no on this one. A poor recording is a poor recording. The system can't put anything there that isn't there. It is my belief that the measure of analog is analog. That is you don't really see the value of analog so much from comparing it to digital recordings as in comparing good analog recordings to poor or indifferent ones. I think this is what really makes you appreciate the artistry of producers and engineers in getting sound onto an analog medium. I recently had a general upgrade of my system that particularly improved the analog side, and it is quite the experience to listen to a record you know of old find it sounding better than it ever sounded before. But when played through the same equipment you will find that there are recordings that just fill the room and there are others that lay there like a lump. One thing I've been doing as I revisit my LP collection is listening to the English folk music I love, and I still love the music but by and large they really weren't that well recorded. On the other hand, while it may just be an effect of what's in my record library, what I've been particularly impressed with are record from the Warner/Elektra/Asylum menage, For example, Paradise and Lunch by Ry Cooder, and Swordfishtrombones by Tom Waits. Actually, one of my more unusual analog appreciation moments was listening to an old Alan Sherman record and being struck by how good it sounded.

On the digital side, I once tried something I think of as the DAC/CD Death Match, when you take an early digital recording you know to be pretty dire and run it through a good DAC to see if it can be redeemed. My match was a Denafrips Ares II vs. the extraordinarily harsh MCA Broadway Gold digitization of the original cast album of Porgy and Bess circa 1992. I'm afraid the CD won that one.

yes I totally agree garbage in garbage out, I have a $60,000 system which includes a Sim audio p8, Sim audio w8, esoteric P10 transport, Wyred4sound 10th anniversary dac, monarchy audio up sampler, and for the speakers monitor audio platinum 200 Gen 2, a friend of mine brought over some of his CDs that were not so well recorded and boy could you tell the difference from other CDs that were well recorded it wasn't even close.

I've found that most 'poor' recordings only sound poor because the system/room I was hearing them in was not good enough to translate the acoustics of the space the recording was made in. There are much fewer poor recordings than we generally believe exist; and more poor systems/rooms that make us believe the recording was poor. The best sound/room systems accurately allow the decay and reverberation of the recordings to complete what we understand as the soundstage, such that what once sounded like a poor recording was merely an inaccurate or incomplete playback of the uniquely altered sound of instruments and music in the specific venue of the original recording. 

In friendship, kevin.

What I have found is exemplified by my run in with Jimi Hendrix ‘Are you experienced?’.  When I play it on the system I have today (for nostalgia sake) it’s almost unlistenable … harsh, bright, compressed etc … though the music still good.  It just never sounds as good as it did on my parents cheap console system 40 years ago even when my hearing was better.