Slaw - I might be misunderstanding your post but, for me, the gear has had little do with music discovery or a willingness to discover. Whether it was a transistor radio or a crappy little boom box, I’ve been hooked on listening to music from a very early age. Having a decent system makes the experience a lot more pleasurable and definitely reveals more of what’s going on in a given composition...but it ain’t critical. I’d be doing it with a pair of earbuds and a laptop if that were all I had.
I miss WXPN out of the U. of Penn. in Phila. Great source of adult contemporary and indie stuff. Having moved away from there, the Spotify Browse/Discover function has been a great source of new music for me. Also, I’ll yet again mention Richard Allen and the "A Closer Listen" website (a home for instrumental and experimental music). Can’t speak highly enough about this site.
Finally, I probably listen to a broader range of music now compared to 50 years ago but I’m also finding I’ve become increasingly fussy. Not bragging, not claiming superior taste or sensibilities...just seems to be harder and harder to find things that I connect with and draw me in. Oh well...just got to keep after it. There's certainly a wealth of sources for finding something good...the various threads about music here on A’gon are a real blessing in that regard.