I need a pair of headphones for a Pocket pc. I have looked at the ever reliable range of Sennheissers. The highly efficient PX 100 and 200 look great but I am still concerned with the 32 ohn impedance despite their extreme efficiency. The more expensive noise cancelling 250 model look an easier load at 300 ohm but they are MUCH less sensitive. Can anyone give any first hand experience on how these headphones work a simple Toshiba E740 pocket pc please?