Just thought I would give an update in case this can help others in the future.
Turns out it wasn't the power line at all. I pulled out my feed line away from the only nearby power line but still had an issue.
I then realized that the breaker also had power to my office 2 floors up. All kinds of computer equipment up there.
In the end it turned out to be a combination of 3 things. One was the hall light, one was a couple of IKEA halogen lights, and then the biggest culprit was an old (15 years) network hub. I wasn't even using it at the time, just had left it powered up when I needed it for some quick testing months ago. Pulled the plug on that and the noise dropped immediately. The lights were more of bring down the noise floor a bit which was nice.
This is all because my antenna is almost right above my office on the roof.
Tomorrow I'll be going after the smaller yet still annoying RFI issues. I'm realizing that this is the never-ending quest of a ham to get rid of this stuff. I'm betting new RFI sources come and go all the time. Hopefully not too many from the neighbours.
Thanks again for the help!