Need help diagnosing an issue

[Nickanator8]

Hey guys, so my 160k 2000 Boxster S has developed this awful low drone that presents at speeds above about 20 mph and gets worse the faster you go. The noise presents whether I am in gear or not and seems correlated with vehicle speed, not engine revs.

I did some Googling and it sounded like the wheel bearing might be the most likely culprit, but I jacked up the car and gave all four wheels a wiggle and they are solid as a rock. I took it out for another drive on a deserted road and started weaving back and forth to load and unload the wheels. When doing a hard right and loading the front left wheel and unloading the rear right wheel the noise goes away. It's definitely something that corner but when I visually inspect it I don't see anything obvious.

Any ideas what it might be or perhaps other tests I can do to more accurately diagnose the issue?