I love this thread; it gives me hope that music will survive as a support pillar in the aging process. Speaking of aging...I just had a medical scare that could have derailed my studio plans permanently.
I spend some of my time on audio engineering webs, and pick up good bits of pieces on mixing, mastering so when my studio is finally functional, I will be starting the process above zero. In one of the posts, someone mentioned that he doesn't hear some high frequencies out of one of his ears, which is a problem when balancing a mix. Just for shiggles, I downloaded a frequency->wav file generation program, and decided to give myself a hearing test by panning different single-tone frequencies from left ear to right ear and back, to try to get an idea of my hearing without having to go to an audiologist since, (despite my wife's insistence that I am deaf when she demands things), I'm not aware of any major problems yet.
I set out creating a range of tones, 0-500hz, 500-1khz, 1k-9khz, 9k-15khz, 15khz-20khz. When I got to the 9khz test, I discovered that the tone disappeared when I panned from right to left ear, and reappeared back at the right ear. Above 9khz, nothing from either ear. Hmmm. This is bad. Bumping the volume did nothing.
Woof. This is bad, and I have my 'best' (most expensive) earphone headset on to keep my experimenting from driving my wife insane. In desperation, I bailed on the earphones, went down into the basement storage, and found a pair of decent range speakers with three frequency ranges (piezo, midrange, and a ported bass), and hooked them up. Bingo. The 9KHz is back, and the 15khz is 'iffy'. To see how bad my mixes can be, I took one that I recently did (which will have to be completely redone now that I know my earphones are bad), equalized everything above 12khz to zero, and the mix came out absolutely boring and flat. I don't know the DB loss range, but it isn't so bad as to be missing. I may never be a master at mastering, but at least I know my mixes won't be totally devoid of high-frequencies.
The moral of the story: don't EVER use headphones in a final mix. Not only does the mix sound 'less than good' on speakers, but you never know what your missing.