Would it be possible to just take the tape off of all three holes, cut it into pieces, and then cover two of the holes?  I know it's possible, but would it be practical?  Also, what do you mean by "Blue Tack"?

I have a pair of 439s and I'm interested in this mod.  However, this is my first pair of "nice" headphones, my first step into the audiophile world.  I listen to a lot of dubstep, techno, house, edm, etc.  Lots of bassy music.  I want to do this, but I don't want to screw up.  When I was trying...