It's a bit unfair to compare SR-80, Stax's lowest end model long since out of production, to Sennheiser HD650's.
Stax hasn't made a self-charged electret model headphone in a long time. Electret headphones have internal charge. This usually requires physically thicker diaphram, resulting in less extended response, and the often the charge dissipates over time anyway, losing dynamic range.
Plus the SR-80's had a transformer type stepup box. All Stax's sold now have tube or transistor based stepup devices.
I picked up a pair of SR-80's on ebay around 2005 for about $50. Current top Stax package goes for $4650.
Stax hasn't made a self-charged electret model headphone in a long time. Electret headphones have internal charge. This usually requires physically thicker diaphram, resulting in less extended response, and the often the charge dissipates over time anyway, losing dynamic range.
Plus the SR-80's had a transformer type stepup box. All Stax's sold now have tube or transistor based stepup devices.
I picked up a pair of SR-80's on ebay around 2005 for about $50. Current top Stax package goes for $4650.