Bike noise, creak, click, creaks, clicks, clicking, pinging sound - help

I used to have wheel pinging, it was a non-consistent noise per revolution on a pair of Mavic Ksyriums. Drove me mad.

Could be a few things from what I've read about:
-Spokes not properly stress relieved
-Hub bearings not properly preloaded (although I think you mentioned you had cartridges) I didn't have the mavic key with me so couldn't test this
-Flat spokes rubbing up against each other and at the spoke holes at the hub - this was my problem, a drop of dry lube at each spoke intersection and most importantly at the spoke/hub interface solved it all for me (mavic k. hubs have a spoke cover thing)

This all being said, ksyriums seem to ping often for a lot of people, not sure if that relationship can be extended to a mavic rim too.

MishMash

About 1 week ago my front wheel (I think) appeared to develop an annoying creaking noise mainly when standing on the pedals and leaning on the bars eg climbing hills, starting off at lights. It sounds a bit like the spokes pinging as they bed in, if not stress releaved enough when building the wheel.

The wheel has 28 spokes (DT Champion 2mm I think) and these are radially laced to Mavic Open Pro rim and an unbranded hub. The cartridge bearings appear to still be butter smooth. I've checked the rim and hub shells for cracking - none evident. The wheel still runs true with an average spoke tension reading of 24.7 on the non-drive side and 25.4 on the drive side (both measured on the Park Tool gauge).

I've also checked that the SKS mudguard is not creaking at the fastenings and it appears to be silent. I'm now stuck for what to check to stop the annoying noise and it's driving me mad. It's not loud just annoying as I know it shouldn't be there and wasn't there.

Any suggestions other than ear defenders?