Ian, your request for a car radio with inputs is umong one of the most
highly regarded requests for audiophiles and like to use devices (or
other radios) to add to there current car setup for external "goodies"
that either you or friends (or work) has to offer for sound. Pioneer
has whats called an IP-BUS that is a special port built into most of
their head units that allow a module (again from Pioneer) to be
plugged into directly to the head unit for external RCA jacks to be
used as input for the sound system. I have installed a system like
what you are asking about just 3 days ago and I have a laptop and
Mini-disc players and other goodies that I use in my truck as well.
There are two different modules that you can buy from them (available
at most Pioneer resellers and installers) they are the CD-RB10 (just
has the left and right RCA jacks on it) and the CD-RB20 (which has the
RCA's but also an IP-Bus passthrough which still allows the head unit
to control a CD-Changer from Pioneer (which is the original operation
for the IP-Bus). I hope this answers your question. In short, yes they
are available its just that most of the units now have the option to
"add" it via ports in the back of the unit. Still others used and some
still do offer a headphone jack in the front face acting as an input,
although these as you have found are becomming increseingly rare and
most makers have opted for the plug-in add-ons instead. Hope this info
helps you Ian. Good Luck, Jason