Bshapperd, am I correct in assuming that the Simaudio Moon is your current phono pre?? Notwithstanding whether it is or isn't, I own the Zephyr - as I've already mentioned above and am pleased with its performance on my VPI Classic. It's output is 2.3 mV and requires a pre that has 47K ohm input impedance, which means that most phono pre's should be able to handle the carty. [As an fyi, the DV 20X2 is my backup carty.]
I think the more important question is whether the phono pre/linestage you're looking at will mesh well with your amp. That changes your question around quite a bit.
Although my phono pre is an ARC PH-7, soon to be PH-8, I wouldn't recommend it because I don't know how it will work with the rest of your gear -- as just explained.
And one bit of advice, if you open-endedly ask what is the best [insert: line stage, phono pre, amp, etc], you'll get a million responses. I generally refrain from answering those types of inquiries unless I strongly suspect or know that a particular combo is a natural fit or a bad fit.
Good luck.
