I have to agree with xcool, a great thread and informative. To the OP's original question, are high end amps a waste of money if you have hearing loss, my experience says no. I developed tinnitus in 2011 and went to an audiologist who measured my hearing. Other than the high frequency loss from old age, I have a moderate loss at lower frequencies (around the typical vocal range). Not severe enough to "require"' hearing aids but easily measurable.
Both of my 25 year old amplifiers quit last year so I made an upgrade when I purchased new this year. I could hear the difference, better detail and bass are obvious even with my somewhat defective hearing. So, for me, the extra expense was well worth it.
Jim S.