(Follow-up to this post
https://albert71292.livejournal.com/1639795.html ):
Just "tested" the old Kenwood cassette deck from the late 1990's, which hasn't been used in at least two decades. It powers up, but the deck bays no longer work when "Play" is pressed.
Sometime later, I'll see if I get full stereo sound out of the ION deck using the RCA to 3.5mm cable, since I currently don't using the USB interface. If not, guess I'll buy a new cassette deck after I get my first SSI "back pay" check.