In that case I will burn mine, i just bought it and it doesn't sound as good as I expected it to be.
Yes, actually my MP21 was also not sounding nice before. I thought I wasted money in it though its MIC is very good, I find it useful for chatting. People says that PL21/MP21 have good bass response. But i didn't find it. Its sound is very clear, mids are good but lacking in bass.
I in a website found that the basic principal of burn-in is to expose the diaphragm to its extreme point so that it gets softer and smoother to produce nice sound. I connected my MP21 to my Hi-Fi and played the Daredevil Album repeatedly for 8-9 hours with a few pause in between. I played just a little below than the max volume of my Hi-Fi.
And HURRAH !!... MP21 became quite boomy...
Song tracks are :
"Won't Back Down" by Fuel
"For You" by The Calling
"Bleed For Me" by Saliva
"Hang On" by Seether
"Learn the Hard Way" by Nickelback
"The Man Without Fear" by Drowning Pool Feat. Rob Zombie
"Right Now" by Nappy Roots feat. Marcos Curiel of P.O.D.
"Evening Rain" by Moby
"Bring Me to Life" by Evanescence Feat. Paul McCoy
"Until You're Reformed" by Chevelle
"Right Before Your Eyes" by Hoobastank
"Fade Out/In" by Paloalto
"Caught in the Rain" by Revis
"High Wire Escape Artist" by Boysetsfire
"Raise Your Rifles" by Autopilot Off
"Daredevil Theme (Blind Justice Remix)" by Graeme Revell and Mike Einziger
"My Immortal" by Evanescence
"Sad Exchange" by Finger Eleven
"Simple Lies" by Endo
"Let Go" by 12 Stones