"I’m going back to carrying a large portable hi-fi (aka boombox, but the term didn’t exist… ) "
In my day, they were called "Ghetto Blasters" and there was a serious amount of competition, between Sharp, JVC and others as to who could produce the biggest, loudest, bad-ass radio/cassette player between them.
In the end I think Sharp won, with products like the GF-777
http://www.wikiboombox.com/tiki-index.php?page=Sharp+GF-777
And if you needed more speakers, try a Panasonic RX-A5
http://www.wikiboombox.com/tiki-index.php?page=Panasonic+RX-A5
and of course not only were some of these "boxes" physically large, but they also required a significant number of D type batteries, which added to the carrying weight !