Percussion could use a little work - seems a little repetitive, and not enough kicks for a metal song like this. I like the guitar work a LOT though.
Might want to check this beat...
-.,.-.,.-.,.-.,.
K......K.K......
....S.......S...
H.H.H.H.H.H.H.H.
K = kick
S = snare
H = hat
Of course, vary it up, but for this tempo, having something other than straight kicks / hats every beat then a snare every other beat is kinda meh.
Didn't notice anything about a weird buzzing sound, the rest sounds great to me. Did I mention the guitar work is fantastic?