Ah, nice. Thanks for all the info on interchangeability and tips! It looks like I have my work cut out for me. Now is the waiting phase where I wait for my headphones to arrive. Can't wait to get started with modding these! 

  Thanks, waynes world, I'm thinking of switching between them all just to experience the different sounds and try my hand at modding. Do you know if the drivers on KSC75, Sportapro, and Portapro are interchangeable? I'm thinking of swapping out the drivers on the Portapro with KSC75 or...

Ah, thank you all for the replies! Unfortunately I don't think there's a Parts Express here in Singapore/Malaysia region. Perhaps I can go straight for the Kramer mod instead. Now to locate a drill for that purpose...   I keep listening to these headphones, in some music the bass doesn't sound...

Would love to join in if my schedule's not conflicting. :)

AKG K712 over here...oh the sweet, sweet soundstage...

Glad to see these Koss PortaPros (that's been around longer than I have, imagine that!) still kicking ass in 2015. Just got my first pair of PP as temporary 'phones while my AKG K712 is in repair, and to experiment with the more bassy sound in comparison to my AKG (I'm a newbie to headphones)...