High end audio - mid range ears

I've been an interested observer to many threads for a while now, and as much as I love audio, I've come to understand that my experience and budget is really mid-fi at best.  Some of the topics, the gear, and budgets are well above me, but I like to learn.  You guys have a wealth of knowledge.

My interests are way above my current investment, but I've built my systems over the years based on what I can get away with or what an apology can sustain.  My wife, you see, doesn't share my enthusiasm (A Sony clock radio is fine for listening to NPR and she finds all my components and listening zones just too complicated.  Comments like, "How many speakers do you need in one room?" pretty much explains it.)


So here's the thing...
At 62, I'm not a young guy any more.  Though I'm constantly striving for the next level of audio gear I can get away with, at what point is it a losing battle because our ears simply can't hear the frequencies or discern the subtle differences?

Everyone makes sure the audio gear and dynamics of the listening area are matched perfectly, but how -- and I assume everyone thinks about this -- how do you justify better and better technology, when the most critical component will slowly but surely fail to hear the improvement?

Rather than argue pros & cons of a particular pre-amp, streaming device, or cable system, thought it might be entertaining to understand you philosophical perspective. 

I'm all ears...but like much of my gear, they're vintage.