Is *that* why many boomboxes and home stereos(cheap ones) have a tone
knob labeled "Bass Treble"?

All I notices with those is that turning it to the left made the sound
muffled and to the right made the sound more tinny/hissy. I didn't
notice that the bass was being boosted when the knob turned left or
that it was being reduced when turned right.

-CC

These pots on the circuit references aren't on a common shaft.

In other words, you can have muffled *and* tinny/hissy! ;-)

Dave