That's quite a good experience Wazkelly. I would have thought a heavy hard coat would have killed the higher frequencies rather than the low/mid ones, but hey, you live and learn.
I went to Bunnings today to have a look. They had a RO sander at a very good price, but the guys there put me off buying it. They didn't think it would be worth it for a guitar. I did buy though a 12V $22 polisher, cheaper than getting a buffing tool for my drill.
Also for anyone interested, Super Cheap Auto currently has a very good deal on Meguiars polishing products.
Cheers
Christian