Alpine AiNet aux input adapter SOLUTION!!!
After talking with Alpine tech support, it seems that Alpine HU's that have a setting on the menu to turn the MUTE funtion off, should be able to use the KCA-121B AiNet-RCA adapter to get an AUX input without a CD Changer. The guy on the phone told me that it depends on the model of head unit. If you have the AUDIO MUTE function on your unit and you can turn it off in the menu, you CAN use the adapter. Thank GOD! I was cringing at the thought of using an RF modulator, or having to shell out some $$ for a crossover. Basically, all you have to do is this:
1) connect the external source to the adapter
2) connect the adapter to the AiNet port on the HU
3) turn OFF the MUTE function on the unit
4) find the pink/black audio mute lead (or whatever color yours is)
5) install a switch that switches a ground to the mute lead.
Here's the doc online straight from Alpine:
Hope that helps all you Alpine users!!! (or anyone else with an AiNet port and no aux jack/hack).