creak and groan

[Science]

My almost new CrankBrothers Iodine headset like to creak and groan and carry on under high stress events such an endos and heavy braking.
I got the Iodine rather than the cobalt as i wanted the bigger set for the all purpose riding i do on this bike, so it should be coping.
The fork is a RockShock SID Race, and the frame is a medium Marin Palisades Trail, Stem is a Thomson elite.

Any ideas on stopping the creaking?

 

[SuperSix]

did you grease/lubed the bearings properly?

Are the cups/races properly seated?

 

[AngoXC]

Don't dismiss damaged/ovalised head tube.

Your Marin was second hand, wasn't it?

Fault in the fork crown could be a possibility too?

Many variables.

 

[Science]

Don't dismiss damaged/ovalised head tube.

Your Marin was second hand, wasn't it?

Fault in the fork crown could be a possibility too?

Many variables.

The frame was second hand, but it was unused and stripped for parts by the shop