Creaking sound when pedaling [audio clip included] Something is creaking on my Cannondale while pedaling with force. It is easier to hear in low gears, when climbing. An audio clip tells it better than any literal description, so here is a recording of me climbing a steep slope: Recording
You can hear it starting from second 7. I held my phone over the crankset.

If it matters, I run Shimano 2×11, FSA MegaExo BB, DT Swiss 350 rear hub. Drivetrain elements such as chain,chainrings,cogs, pulleys are thoroughly cleaned to look and work as new. Some months ago I cleaned and lubed the BB, chainring bolts and pedal threads. The creaking is also happening while standing, so it’s not seatpost related. Yesterday I also lubricated the rear wheel nipples(WD40) and also placed a drop of lube on the contact points between the spokes, with no results.
Any ideas ?
I found the culprit(most likely): it was the cogs digging into the freehub body, as seen in the post here. I imagine the cassette lockring wasn't tight enough. The recommended torque is 50Nm but since I don't have a torque wrench that big, I've tightened it how tight I believed was enough, last time I removed the cassette. 
At the time of removing the cassette, I've also greased the derailleur hanger bolt and contact surface, and the skewer, but I believe the noise came from the cassette.
Sorry for wasting your time !