Pkelly, I'm wondering if with your present CJ ET3SE you are having to operate the volume control undesirably close to the bottom of its range, especially with digital sources if you are using any.
The reason I ask is that your ET3SE, and also the ET5 you mentioned as a possibility, are spec'd as having unusually high gain (25 db). And I see in another of your recent threads that you are using Sonus Faber Elipsa SE speakers, rated at 91 db/2.83V/1m and 4 ohms, and Cary CAD 500MB amplifiers rated at 1000 watts into 4 ohms, with 1.42 volt sensitivity for full output power. That all suggests to me that you may have too much gain in your system to be optimal, and the same would be true if you went to an ET5.
The 12 db gain of the PrimaLuna preamp, which is more typical of the gain of most line stages, seems much more reasonable in the context of your particular system. To be sure it's clear, however, in saying that I am not expressing any opinion about the PrimaLuna's sonics, having no experience with it.
FWIW. Regards,
-- Al