i just got a pair of PX100's and love them, but found them too dark for my tastes stock. here are some mods i did to try and make them more balanced, and they sound much nicer now.
first off the quarter mod: cut a quarter size hole in the middle of the pads:
now here is one i found on the internet, you basicaly remove the foam from the back of the drivers, with a pair of pliers it is very easy to remove all of it.
and here is on that i did myself, and it opened up the highs a little bit and tightened the bass i think. what you do is take off the pads and at the bottom of the driver there are 2 holes, you cover them up with tape and i put some hot glue just to hold it better too.
sorry for the bad quality pics, phone isnt very good.
a brief review:
very nice sturdy cans, the hinges and folding mechanism clicks into place nicely, and the hinges are not loose or anything. and the hard case is a nice addition, to protect them, the only negative would be the thin cable, and there is much strain relief on the mini jack, but going into the driver housing the strain reliefs look sufficient.
stock sound: dark, smooth, laidback. there is some nice punchy bass which dips down nice and low, and is not one note bass, the mids are smooth and laidback, and the highs are slightly recessed, with little detail. overall a very non fatiguing lightweight, super comfy portable headphone.
with mods: the highs have appeared a bit, and now they are more balanced sounding, with some nice sparkle, the mids stayed nice and smooth, lush sounding, and the bass has tightened. overall still a dark sound, non fatiguing, but with more highs and tighter bass than stock, im very happy with them now.
thank you for reading, hope you enjoy.
regards, fellow headfier Oscar