That doesn't mean either of you have poor hearing. There are so many things at play. I think it's important to realize that hi-end Hi-Fi is a hobby and is totally unnecessary for musical enjoyment. Most people know this and are puzzled by the audiophile's reluctance to admit it.
We don't need to have a Hi-F system spell everything out for us. We instinctively know what people and instruments sound like and our brain fills in what is lacking when we listen to music on more basic replay systems. You remember rocking out to the cheap stereo in your bedroom as a kid? The music in the car? A portable radio in the shed or garden? As long as the basics are straight our brain fills in the blanks and tells us there are real artists somewhere behind the veil.
Ironically, a 'better' system can actually make things worse. Because it lets you hear so much more it, becomes harder to hide the fact that you are listening to a recording and not real people. Some systems are worse in this regard than others but this is why a simple system can play any disk while 'better' systems sound terrible on poor recordings.
Your eyes do a similar thing. You have a blind spot in your vision and most of it is monochrome but you don't realize it because your brain fills in what is not there. It's quite remarkable.
So it's not weird that your wife is happy with her simple system. It's us who are the oddities. We spend large sums of money on music systems that are at the end of the day, pointless.