First, I have not used any pink noise or or any other burn-in mechanism other than playing music through them for my pleasure. I don't think they've changed much if at all since I got my V5 drivers, so my vote is no, there is no burn in necessary.
Second, the L-cush Grado pad is the best pad for the Magnum V5...the other pads don't even come close in my opinion.
Lastly, I have found that the source makes the most difference for the Magnum. I happen to use an Aune T1 which is a USB Tube DAC and solid state amp combined. It's the best thing I have heard for my Magnums. Check the Aune T1 thread here:
CLICK HERE.
Feel free to PM me with any questions!