[gvel]

I still have some buzz, but it is about the same it was before

Sorry...I've never heard AC hum referred to as a buzz.

Line filters were around long before switching power supplies. Further, a lot of radios used line filters, to remove "local interference" from finding it's way into the radio's front end, via the line cord. Back then - "safety caps" were not available - so wax/paper caps were used. Today, when these are replaced, most use X or Y rated capacitors. Others don't bother and substitute with a poly cap.

My TRF, an Amrad Model 70, originally did not have a line filter either. Like I mentioned, it had a horrible "buzz". After I was enlightened, I added a line filter, and my problem was solved. It's so quiet now, I hear very little in between stations.