Actually the buzz has two main components: the harder to listen to is the high band 13000-17000 with frequent bursts of 16 000 after noise reduction. The low hum is less troublesome. With AA2 you have two options : the automatic click and pop eliminator gives good results but I got better with noise reduction. I attached the fft file which you can upload in the "noise reduction" window after unzipping. You'll get even better results by resampling the noise curve from a silent bit of the audio (with noise) --as your file did not have real "silence" in it I sampled the noise as I could. Other parameters should work fine, adjust them to your taste. You can preserve much of the spectrum up to 4000, it only gets worse above that. Then you'll probably wish to apply a hard compressor to high frequencies above 12000 to limit them at -75dB (dynamics processing). Doing that, spectrum analysis shows that you still retain most of the dynamics of your file up to 8000 or even 10000.