I'll make an exception in this case... I guess traffic in Audio / Security is down. h:
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To get reliable 12V power, I'd run a power lead directly from the positive side battery clamp through the firewall to the modulator.

In the 94-01 Integra, there's a nice grommetted port in the firewall right behind the battery tray. Run your power lead right through the rubber plug to protect it from the metal edges. To make things easier, a commercial amp installation kit (like those available at Best Buy) will have a power lead pre-fabricated with a fuse holder installed. I'd start with that.

BE ABSOLUTELY SURE TO INSTALL A FUSE ON THIS LINE, just as you would do for an amplifier install.
I cannot stress this enough.
Failure to do so could result in a fire.
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I assume this modulator is for an add-on CD changer?