Installing 2 head units possible?

Hey everyone. I was wondering if it was possible to install 2 head units in a car. I've got a 2002 Elantra GLS (same thing as an '01 in anyone has one), and I've got a minidisc player which is great for MP3 stuff, but I wanna put in a Pyle pop-out LCD which controls a Pyle CD-Changer (got both really cheap off of ebay). Now, I've looked, and the opening for the pocket under the  main player is the same size as the main player. So, here are my questions:

2. I will hafta create a switch board of at least two 4-poll, double-throw relays for the speaker. Will I need an additional relay for power, antenna, etc.?

Thanks alot for ur time. Any help or suggestions would be greatly appreciated.

-Matt

What I've done in the past is have both systems piggyback the speaker wires and only have one system on at a time. You can't have both playing any way so have one off and have one on. You can set up a relay that will automatically turn one on once the other is off via the remote turn on lead. As far as the antenna, designate one as your tuner and use just the one for that purpose only.

There are switching units available for both high level and low level sources that will allow you to safely run two head units in one system. Here are just a few:

http://peripheralelectronics.com/2002/signal_path.asp

also there is a relay with 12 lags you need two of them

very e/z to do

i have done many        never had any problem