I often have older customers tell me they don't want to spend a lot on gear because their high frequency hearing is diminished and they wouldn't be able to appreciate the quality it offered. WRONG! To illustrate the point let me recount an experience I had early on in my audio career.
At 18, and just out of high school, I went to work at the local high-end shop (we didn't use that term then, but we handled McIntosh, Klipsch, Marantz, etc., so I guess we'd fit that description today). The owner was a good friend of Paul Klipsch and Paul would visit the shop from time to time. Mr. Klipsch was a pilot and owned a small private plane that he flew regularly. I’m told that instead of using headphones to monitor radio transmissions, Paul preferred a midrange horn (or, squawker as he called it) out of a Klipschorn. I can imagine how loud that must have been to hear the radio over the engine noise! Considering that, and his rather advanced age, I'm sure Paul had "zip-o" for high frequency hearing.
On one visit, Paul, and the rest of the crew at the shop were chatting and enjoying some tunes when Paul lept out of his chair shouting "Did you hear that? Play that part again!" We cued the cartridge back a bit and replayed the section, again with Paul exclaiming about what he'd heard - the rest of us struggling to perceive what he was describing. After several plays I could pick up a small amount of distortion that he heard immediately. Here I was - with pristine 18-year-old ears - struggling to hear the minutia that a gentleman approaching 70 picked out in an instant. It was a great lesson and taught me that "hearing" was more of a learned skill than an innate ability determined by physiological assets.
The subtleties that a high resolution system can deliver should not be thought of as exclusively high frequency events requiring bat-like hearing to recognize and appreciate. Rather, a great system reveals a multitude of aural delights easily perceived and enjoyed by people with a broad range of hearing. Audophiles who’ve trained themselves to “listen” easily hear and appreciate the nuance that a high resolution system can offer. It does not require 20Hz - 20kHz hearing to appreciate and enjoy a high end audio system.
Developing better listening skills takes practice. And, unlike the piano lessons your mother made you take as achild, this practice is a blast! Simply enjoy mlistening to your system. The more you listen, the more you will become familiar with the system and the way it conveys the emotion of music and its ability to resolve information. With that knowledge you'll not only appreciate music to a greater degree, you'll have a better handle on which direction to take as you upgrade your system.
Though I've never really thought about sitting with the intent of becoming a better listener, as I think it comes naturally with time, some of the more detail-minded among you may prefer a more structured approach. To that end I offer an article written by Mr. Peter Cuddy who outlines specific steps to guide you through a listening session.