Update: I got the Z-150.4 II amp installed and something strange is going on. My HU is an DEH-80PRS running a 3 way active setup, internal amp is off, so I should have a clean, unclipped signal at 61/62 volume. When I went to set the gains using a 1Khz 0db signal and the HU volume at 61, per my O-scope, the signal clipped with the gain turned all the way down, amp crossover settings set to 'Full', 'multipliers' set to '1X'.

I doubled checked the HU was set to flat and everything else was at 0, position setting was off, Auto EQ was off. I even did an Audio Setting Reset and tried again - the same clipping issue occurred. I had to turn the volume down on the HU to about 52 to get a clean unclipped signal using 1khz at 0db with the gain all the way down. And the other odd thing is that the sine wave displayed on the scope, while not clipped, were not a smooth and uniform wave. It seemed to have a dip right after the peak.

I used this O-scope on other amps using the same set up and have never encountered this before.

I did end up setting the gains to a non-clipping setting using 1khz at -5db. As far as I can tell everything sounds good, great in fact, and I am not hearing any audible distortion, but I am still wondering if the amp is defective?