Total noob... I'm a geek (went to school and worked in IT for a number of years), but I can't wrap my head around the whole electronics side of this...   Just picked up the Sennheiser HD 280 Pro Impedance - 64 ohms Long-term max. input power - 0.5 W Frequency response (-10 dB referred...

Completely new to all this and a bit confused with all the terminology and whatnot...   I'm looking for full size headphones that will run off my iphone that are less then $100   I had been leaning towards the Sennheiser HD428s, simply because you can pick them up for $50 right now...