8600 Balanced input problems

Thought I would post here before opening a "ticket". I am been a long time Flex user. I am primarily an "AM" operator. I therefore use a lot of processed audio thru the TRS Balanced input. Normally (on the 6600) I can dumb 0 db into the TRS input and with the mic slider achieve 100% modulation with lets say a setting of 30. With a level of -5 on the mic level meter. With the 8600 the mic slider has to be set at 2 to achieve 100% modulation and the level meter reads -15??? Also I did need to set the mic slider at 30 it it was running OK then all of a sudden it went into over modulation and I had to turn the slider down to 2. No matter I cannot set the input so I see -5 on the level meter. NO the 20db mic gain is OFF. Thanks for any help. Waited a loooooooooooooooooong time for this radio and this is disappointing. Anybody seen anything like this with an 8600??