I have not replaced the component speakers in the door of my prelude but I do know a little bit about the back speakers. They are 2 Ohm speakers that are part of the acoustic feedback system. I believe you need to take out or rewire the speakers so they do not use the amp for that system. Are you replacing the front speakers with component speakers?

Here is a site that explains the replacement of new speakers and/or head unit in a 5th generation Honda Prelude. It also explains the Acoustic Feedback System.

http://bellsouthpwp.net/v/i/vidgamer/preludeaudio.html