There was most deinitely a problem with daisy chaining the EP600 when Mojo and I were doing the sub comparisons. It was thought that the latest batch of amps with the higher filter(150hz) on it and no by-pass mode solved the issue, IIRC. I seem to remember a couple of posts by a few owners with the newer amp design and they were able to daisy chain the 600 without the drop out of the other subs.