I’m the same age, but my tastes are a bit different -- more classic rock, jazz, and classical. Still, there are many things which are not that well recorded or were compressed for playback on commercial audio such as car stereos, beach radios, etc.
The bright spot in this for me has been finding more and more recordings which were remastered with some care. (Not all remasterings are done this way; many are mere marketing gimmicks.)
I’m not sure whether Heavy Rock (as you call it) has had the benefit of such remastering efforts as other bands such as Yes, Jethro Tull, etc. Maybe that’s worth some internet research.
One question for you -- why do you have a DAC that is so many times more expensive than your speakers? I'm wondering if you might be a candidate for some changes, there. Just a thought.