all and all, the zapco is just a better amp all the way around. at lower ohms, they are actually louder. the reason JL's operate at lower ohms like they claim is that they actually back off slightly powerwise so that way they dont heat up and shut off.
so at 2 ohms, the JL is not putting out the full 500 watts that it is capable of, the zapco on the other hand makes more power at 2 ohms than the JL does because it is designed to run at 2 ohm and deliver 500 watts at 2 ohms. just because the JL can operrate at 2 ohm or even 1.5 ohms without shutting off doesnt mean that you are getting all out of it that you can. we will never shut off between 1.5-4 ohms sounds good to buyers. all marketing. at 4 ohms though, it is a good amp.