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?