So how can a great system solve less than great recordings

FWIW, I have found that as my system gets better, my music also sound better. Of course there are some which don't sound as good as others. And some are just...YUK. But the vast majority sound good overall. 
Some may hear it differently. IMO, Some are more into the sonic character of the music more than the music itself. I am into the music itself. I have no desire to hear a  great sounding recording that does nothing for my soul. IE, I don't play Female vocals and have no desire to listen to that. It doesn't move me, no matter how good the recording is done. If someone else enjoys it, then fine. I'll take the lesser recorded music

Get ROON, can use the digital equalizer to fix the poor quality. It works great

I dunno. How?
Your statement reveals nothing.

Which is why "audiophiles" get siloed into listening to sonic spectaculars. On most boards I participated in, I usually put up a thread called "Non-Audiophile Records" to discuss standard issue pressings from back in the day. 
I take the good with the bad. I'm not a Stones fan, but the early UK boxed label (stereo) is a decent sounding record to these ears, though I haven't listened to it in quite a while.
Ditto, the UK first press of All Things Must Pass has some body and dimension that is sorely lacking from the US copies (bought one of those when it first came out). 
Which takes us into the thicket of finding desirable pressings of records, a subject that is bottomless. 
I find lots to listen to; at the moment, "used" record prices are inflated and desirable or rare records are more expensive than ever. 
My sweet spot, musically, for the last 4 or 5 years has been so-called "spiritual" or "soul" jazz from the early '70s-- that stuff has gotten astronomically priced and many have never been reissued. 
It's fun to find a killer obscurity, especially if it's not on everybody's radar. 
But, there are some records that just sound lousy and if you like the music, you focus on that, not the sonic demerits. 
I used to keep a shelf of known impressive sounding records for demo purposes. I gave that up a while ago-- I just listen to what stirs me and buy what I can, notwithstanding the market. 

OP, if you tune your system to a very high state of tune, you can get to the point where only a handful of recordings sound good. Been there done that. The best tune in my opinion is when only a handful of recordings sound BAD. Work towards making everything sound good even if you loose a little detail or shimmer.