I am using the Senn ME66 (phantom power only, no MZQ200 stand adapter) with the Z7U. The Senn manual says "Sensitivity @ 1 kHz is 0dB (K6-CL -18dB)" Should I set the Input Trim to -18dB?

When I leave it at 0, the recorded signal (when played back), seems to be at least 10 dB lower on average. Thank you for any related experiences you can share with me.

Rather than choosing a somewhat arbitrary sensitivity, I would approach it from the perspective of trying to establish what a "normal" recording scenario would be for you, set the on camera manual audio gain adjustment to around 7 and modify the sensitivity to get an input level of ~ -18 to -12dB on the meters. This should give you enough latitude to make adjustments under normal usage and should provide the best dynamic range (ASSUMING that Sony uses the 70% = unity gain approach in the Z7 - haven't used one - only have time on the Z1U in the Sony HDV line).

Hope this helps.