We are getting pretty much the same result with three different mics: Sennheiser G2 wireless lavaliers, Audio Tecnica wired lavaliers (model number unknown)and an Audio Tecnica AT897 Shotgun. All three of these mics are professional level products and have performed very well with previous cameras.
We have moved the trim to -56dBu and are getting better results. we are going to try to carve out some time for additional testing. It just seems strange to me that the Sony manual states that a with the trim at the default of -41dBu and a volume control knob level of 5 should produce 0dB and a volume control knob setting of 10 should produce +12dB, when we are having to boost the trim 15dBu and are still not quite at these levels using a broad aray of professional level mics. In theory, this represents an 18dB boost to get full sound. We are concerned that boosting the trim much further will result in excessive background noise pickup and/or clipping. I will try to post up results after our testing session.