Any hints at this noise? Cannondale supersix:


                
            


Tried to replace the crankset 
Replaced the bottom bracket with a new one
replaced the pedals
overhauled the headset


The noise only manifests when a relatively higher torque is applied and it doesn't matter if seated or standing. Moving the weight around the bike while pedaling doesn't have any significant effect on it either. 

Thinking about replacing the wheels and QRs and the derailer as soon as I can get my hands on spares. 
I thought that the noise is so specific and strong that maybe it is a recognizable one so I can ask for a shortcut.

Update: tracked down to the wheels for now. Spare wheels make the creaking go away.
If the noise appears when you create more torque it's almost certainly bottom bracket or crank related. You can get creaks in the rear wheel but they tend to manifest in lower gears because that's when the torque on the rear hub is highest.

Cannondales are fairly notorious for creaking in the bottom bracket. The problem is that the bearing cups are slightly oversize which allows the outer bearing races to move. Bottom bracket bearing replacement would not necessarily fix the problem as the cups remain oversize.

Chainring bolts can also creak so remove, grease and re-torque those to rule that out as the cause before purchasing more expensive parts.